ExperimentalInvestigationonSeismicBehavioursofReinforced ... · 2019. 12. 29. · seismic loading tests of eight full-size corroded RC short columns,VuandLi[19] ... load-bearing and

Research ArticleExperimental Investigation on Seismic Behaviours of ReinforcedConcrete Columns under Simulated Acid Rain Environment

Hao Zheng 12 Shansuo Zheng 12 Yixin Zhang 12 Yonglong Cai13 Ming Ming12

and Jingliang Zhou12

1School of Civil Engineering Xirsquoan University of Architecture and Technology Xirsquoan 710055 China2Key Lab of Structural Engineering and Earthquake Resistance Ministry of Education (XAUAT) Xirsquoan 710055 China3Arup Wuhan 430022 China

Correspondence should be addressed to Shansuo Zheng zhengshansuo263net and Yixin Zhang zhangyixinlivexauateducn

Received 29 December 2019 Revised 11 February 2020 Accepted 20 February 2020 Published 25 March 2020

Academic Editor Xiaodong Hu

Copyright copy 2020 Hao Zheng et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

e purpose of this paper was to systematically investigate the influence of acid rain environments on the seismic behaviour of areinforced concrete (RC) column Six RC column specimens with shear span ratios of 284 were tested under low cyclic reversedloads after being subjected to accelerated corrosion tests in an artificial climate e corrosion level and stirrup ratio were used asthe control variables e corrosion ratios of the longitudinal rebars ranged from 0 to 1317 and the corrosion ratios of thestirrups varied from 0 to 675 e seismic behaviours of the column specimens were analysed with respect to visual damagefailure mode hysteresis behaviour load-carrying capacity deformation capacity stiffness degradation and energy dissipationbehaviour e test results showed that the appearance characteristics of the six column specimens exhibited varying degrees ofvisual damage as a result of the simulated acid rain exposure All six specimens were dominated by similar flexural-shear failuresunder low cyclic reversed loads regardless of the distinctions in the corrosion levels or stirrup ratios For the specimens with thesame ratios of stirrup as the corrosion level increased the load-carrying capacity deformation capacity stiffness and energydissipation capacity were continuously decreased For the specimens with the same levels of corrosion the higher the stirrup ratiowas the stronger the restraint effect of the stirrups on the concrete and the seismic behaviours of the specimens wereobviously improved

1 Introduction

With economic development and population growth acidrain pollution has become one of the most intractable en-vironmental issues in many countries and regions [1 2]Furthermore acid rain tends to spread and worsen [3ndash5]Acid rain not only threatens natural ecology but also has asignificant influence on building structures It is well knownthat acid rain exposure is one of the primary durability issuesfor reinforced concrete (RC) structures and acid rain ex-posure leads to the deterioration of the mechanical prop-erties of concrete such as its compressive strength andelastic modulus [6 7] and to the corrosion of steel bars [8]Over time the reliability of an RC structure in an acid rainenvironment gradually decreases hence it is of great

importance to conduct in-depth and systematic research onthe seismic behaviours of RC structures exposed to acid rain

e influence of acid rain on the material-level behav-iours of concrete has been a popular issue for the past fewyears including studies on surface morphology [9] corro-sion mechanism [10ndash13] damage testing method [6]compressive strength [6 14] elastic modulus and fracturetoughness [15 16] Hill et al [9] reported that spalling andcrushing of concrete cube specimens caused by sulfate andacid exposure initially appeared at the corners and edges ofthe specimens Light optical microscopy combined withchemical analysis was used by Gregerova and Vsiansky [10]to detect corrosion products of concrete under sulfuric acidexposure In addition they believed that the deterioration ofthe macroscopic mechanical properties of concrete was

HindawiAdvances in Civil EngineeringVolume 2020 Article ID 3826062 15 pageshttpsdoiorg10115520203826062

essentially caused by the accumulation of microscopicdamage Xie et al [11] carried out an accelerated corrosiontest by using a mixed solution of sulfuric acid nitric acidand ammonium sulfate to simulate the various deteriorationstages of cement concrete specimens during acid rain ex-posure e corrosion of concrete by a simulated acid rainsolution was divided into three stages the neutralizationdepth of specimens can be expressed as a function of thecorrosion time and the deterioration of material propertiesof specimens was caused by H+ dissolution damage andSO 2minus

4 expansion damage Chen et al [12] also noted that thedegradation of the mechanical properties of concrete ce-mentitious specimens subjected to simulated acid rain ex-posure resulted from the coupled effect of H+ and SO 2minus

4 andthe deterioration accumulated from the outside to the insideof the specimens Okochi et al [13] experimented with theinfluence of acid deposition on a concrete structure by usingan indoor spray test and a field exposure test eir resultsshowed that the higher the concentration of H+ andSO 2minus

4 was the more severely the concrete was corroded Fanet al [6] conducted a range of tests on 354 concrete prismaticsamples with dimensions of 150mmtimes 150mmtimes 300mmUltrasonic testing technology was a reliable method for thenondestructive measurement of damage depth and thedamage index corresponding to the change in the relativecompressive strength was more suitable for characterizingthe deterioration state of concrete exposed to acid rain Zhaand Lu [14] investigated the differentiae on account ofexperimental research in the compressive strengths of or-dinary Portland concrete and recycled concrete under ar-tificial acid rain exposure Under the action of a simulatedacid rain exposure significant variations occurred in thephysical and chemical properties of the concrete materialresulting in a corresponding reduction in fracture toughnessand elastic modulus and the lower the pH value the fasterthe degradation rate [15 16]

Conclusively the deterioration of the mechanicalproperties of concrete caused by acid rain exposure has beenfully studied On the component level acid rain exposurenot only influences the mechanical properties of concretebut also corrodes the internal steel bars Less attention hasbeen devoted to the variations in the mechanical propertiesof RC components subjected to acid rain exposure Guanand Zheng [8] employed an artificial climate simulationtechnology to study the effect of acid rain on the seismicbehaviours of interior beam-column joints with differentaxial compression ratios An artificial rainfall device wasdesigned by Fan et al [17] to simulate real acid rain and theflexural behaviours of RC beams operating in an acid rainenvironment were investigated Hence the surface mor-phology and mechanical properties of RC components weresignificantly affected by acid rain

RC columns are the main load-carrying components inan RC structure wherein the columns carry the loads frombeams and slabs and further transfer the loads to thefoundation [18] If some columns failed during an earth-quake the reliability of the whole structure would be greatlyadversely affected An RC column component under an acidrain environment is subjected to the corrosive media of

carbon dioxide sulfate ions and nitrate ions As a result theoverall mechanical properties and seismic behaviours of anRC column component are constantly deteriorated each daywhich gravely threatens the reliability of an in-service RCbuilding structure However for RC columns the existingresearch has focused only on the effects of steel bar corrosionon the behaviours of RC columns Based on simulatedseismic loading tests of eight full-size corroded RC shortcolumns Vu and Li [19] found that the shear strengths anddeformation capacities of corroded columns were markedlylower than those of noncorroded columns particularlyunder high corrosion levels and high axial compressionratios Moreover methods considering the influence ofstirrup corrosion for evaluating the shear strength of shortconcrete columns were proposed Ma et al [20] conductedquasistatic loading tests on thirteen circular RC columnsthat had been subjected to accelerated corrosion tests Onthe strength of the test results degradationmodels of seismicperformance indicators involving the strengths and ductil-ities of columns were presented Li et al [21] analysed theimpact of nonuniform steel bar corrosion on the seismicperformance of RC columns Under the influence of non-uniform steel bar corrosion the seismic performance of RCcolumns after peak points was dramatically diverse in thepositive and negative loading directions In the experimentalstudy performed by Meda et al [22] it was reported that theload-bearing and deformation capacities of RC columnsunder cyclic loading were substantially influenced by thecorrosion of the reinforcement Li et al [23] experimentedwith the cyclic behaviours of eight RC columns with cor-roded stirrups eir results showed that the bearing ca-pacities of columns increased slightly at the outset when thecorrosion ratios of the stirrups were less and then decreasedas the corrosion ratio increased further Yang et al [24]investigated the bending capacities of corroded RC columnswhich simulated a marine environment e hystereticbehaviours of columns deteriorated as the corrosion levelincreased For example when the maximum mass loss ratioof the reinforcing bars reached 168 the bending strengthand ductility coefficient of the corroded column were re-duced by 20 and 321 respectively compared with thoseof the column without corrosion In the above analyseselectrochemical methods were adopted to accelerate thecorrosion processes of steel bars in RC columns and manyachievements were made Nevertheless as far as the authorsknow the study on the seismic behaviours of RC columnscorroded by such corrosive media as carbon dioxide sulfateions and nitrate ions in an acid rain environment has notbeen reported to date

In view of the above accounts this paper aims to ex-perimentally study the influence of the corrosion levelwhich is regulated by an artificial climate accelerated cor-rosion technique on the seismic behaviours of RC columnsunder an acid rain environment In this test six RC columnspecimens were fabricated with different corrosion levelsand stirrup ratios and the columns were subjected to lowcyclic reversed loads e test outcomes are conducive to theevaluation of seismic behaviours for RC structures damagedby acid rain

2 Advances in Civil Engineering

2 Experimental Programme

21 Specimen Details Six RC column specimens weredesigned and made in accordance with the regulations ofChinese codes [25ndash27] e corrosion level and stirrupratio were the controlled variables in the experiments eaxial compression ratios of all the six specimens were 03e geometric dimensions and steel bar layout of the sixcolumn specimens are presented in Figure 1 e crosssections (b times h) and heights of all columns were200mm times 200mm and 600mm respectively which pro-duced the same shear span ratio of 284 e thicknesses ofthe concrete covers were 10mm e longitudinal rebarswere symmetrically collocated ie three 16mm diameterdeformed bars (grade HRB335) were equipped on eachside In addition 6mm diameter round bars (gradeHPB300) were employed for the stirrups e geometries ofthe foundation beams were 1000mm times 400mm times 400mme main test parameters of the column specimens aresummarized in Table 1 Note that the focus of this paper islimited to the seismic behaviours of RC columns with shearspan ratios of 284 under a simulated acid rain environ-ment Moreover the test outcomes of the influence of acidrain on RC columns with shear span ratios of 568 will bereported later

e strength grade of the concrete was C40 which wasformulated with Portland 425R cement e mix compo-sition was 500 kgm3 for cement 559 kgm3 for sand1136 kgm3 for fine gravel and 205 kgm3 for water Twelvecubes with dimensions of 150mmtimes 150mmtimes 150mm werecast in addition to the column specimens and were dividedinto four groups of three cubes each e four group cubeswere subjected to 0 240 360 and 480 spray cycles re-spectively e mean compressive strengths of the concretecubes were tested e results are reported in Table 2Furthermore the measured mechanical properties of thesteel bars are provided in Table 3

22 Simulated Acid Rain in the Environmental ChamberIn recent years artificial climate accelerated corrosiontechniques have been continuously developed and exten-sively employed in durability testing research of RC struc-tures [8 28ndash30] e Model ZHTW2300 environmentalchamber at Xirsquoan University of Architecture and Technologywas used to perform accelerated corrosion tests with anartificial climate accelerated corrosion technique on columnspecimens wherein the environmental parameters (tem-perature humidity and spray solution duration) were set inthe chamber as shown in Figure 2

It should be noted that a secondary casting method ofseparating foundation beams from columns is adopted toprevent the failure mode of column specimens fromtransforming which might be affected by the corrosion offoundation beams e columns were first cast and naturallycured for 28 days Afterward the steel bars located at thebottom of columns were sealed with epoxy resin and thecolumns were placed into the chamber for the acceleratedcorrosion tests e columns and foundation beams were

recast together right after the preset spray cycles werefinished

e confecting scheme of the simulated acid rain so-lution referenced the works of Xie et al [11] and Chinesemeteorological data [31] First to preliminarily form thesolution sodium sulfate (Na2SO4) was added to tap wateruntil the concentration of sulfate ions in the solution reached006molL Subsequently nitric acid (HNO3) with a con-centration of ρ 142 gcm3 was added to the solution toadjust the pH value of the solution to 30 e specificcorrosion scheme is listed as follows (a) e chambertemperature was adjusted to 25plusmn 5degC and the simulated acidrain solution was sprayed for 240min (b) e temperaturewas increased to 65plusmn 5degC at a constant speed and thenspecimens were dried for 96min (c) e temperature wasdecreased to 25plusmn 5degC at a constant speed and a new spraycycle was conducted As described each spray cycle took360min as shown in Figure 3

e corrosion level of the specimens is governed bypresetting the number of spray cycles (0 240 360 and 480)as presented in Table 1 Column SC-1 was used as thecontrol and no corrosion test was performed on thiscolumn

In this paper the precipitation intensity of a certain citywas used to control the period of the simulated acid rainexposure in the laboratory [17 32 33] Chongqing which isone of Chinarsquos largest cities and suffered severe acid rainexposure was taken as the research object and its annualaverage precipitation intensity is about 1100mma [34]During the accelerated corrosion tests the precipitationintensity in the laboratory was set to 345mmh that is thenumber of spray cycles of 240 360 and 480 in Table 1corresponded to the precipitation in Chongqing for 30 45and 60 years respectively

23 Test Setup e schematic diagram of the test setup isillustrated in Figure 4 Linear variable differential trans-formers (LVDTs) were mounted to monitor the lateraldisplacements of the specimens One LVDT was located atthe loading point to measure the lateral displacement of thecolumn top Another LVDTwas mounted on the axis of thefoundation beam to measure its lateral slip In addition twoadditional pairs of LVDTs were used for measuring sheardisplacements and rotations in the plastic hinge areas wherethe length was evaluated as 170mm [35] To simulate theactual load conditions of RC columns under earthquakeexcitation as accurately as possible low cyclic reversedloading tests were conducted on the designed RC columnspecimens by cantilever loading Concurrently the speci-mens were fixed to the strong floor by anchoring screwsthroughout testing processes Vertical loads were applied bya hydraulic jack with a capacity of 1000 kN Lateral low cyclicreversed loads were applied by an electrohydraulic servoactuator with a capacity of 500 kN that was fixed on thereaction wall Lateral push-pull displacements were con-trolled by a sensor

e lateral loading procedure was performed in accor-dance with displacement-controlled steps after the preadded

Advances in Civil Engineering 3

reciprocating load was implemented twice [25] When theresidual lateral load of a specimen was reduced to 85 of thepeak load the loading was stopped e loading protocol isgiven in Table 4

3 Experimental Observations

31 Visual Damage under Simulated Acid Rain e visualdamage to the specimens which had been accomplished bythe preset spray cycles was evaluated as shown in Figure 5It was found that there were noticeable differences in thevisual damage of specimens under different corrosion levelsand the visual damage was continuously exacerbated byincreasing the corrosion level

e control column SC-1 had a uniform concretecolour smooth and flat surfaces and defined corners asshown in Figure 5(a)

e face of column SC-2 which was subjected to 240spray cycles was partially yellowed and accompanied bywhite crystal precipitates as shown in Figure 5(b) In thisperiod H+ in the simulated acid rain solution chemicallyreacted with concrete to form a small amount ofCaSO4middot2H2O crystals covering the concrete surface In ad-dition chemical reactions led to the decomposition of hy-dration products on the surface of the column esephenomena indicated that acid rain caused significantcorrosion on the concrete surface in the early period of theaccelerated corrosion process

As the number of spray cycles increased to 360 sandvoids and pitting were observed on the surface of columnSC-3 and the texture of the concrete became loose as shownin Figure 5(c) is might ascribe to the formation andexpansion of CaSO4middot2H2O and Aft the dissolution of ag-gregates and a continuous variation in the contents of thehydration products such as Ca(OH)2 hydrate calcium sil-icate (CndashSndashH) gel xCaOmiddotAl2O3middotyH2O (CxAHy) andxCaOmiddotFe2O3middotyH2O in concrete due to chemical reactions

As the number of spray cycles increased to 480 thesurface of column SC-4 was rougher than those of the othercolumns and a peeling phenomenon was observed on thesurface of the concrete In addition the texture of theconcrete became looser than that of SC-4 and certain ex-posed coarse aggregates could also be observed as shown in

Table 3 Mechanical properties of the steel bars

Diameter(mm)

Yieldingstrength (MPa)

Ultimatestrength (MPa)

Elasticmodulus(MPa)

ϕ6 305 440 21times 105

ϕ16 373 537 20times105

ϕ6

30

100

400

400

200

ϕ6

608

010

0

2 2

ϕ6

100

1

1

Loading direction 222

422

422

400

1-1

400

222

316

200

2-2

200

316

Figure 1 Geometric dimensions and steel bar layout of the column specimens (unit mm)

Table 1 Main test parameters of the column specimens

Specimen StirrupSimulated acid rain solution

Number of spray cycles Acidification depthValue of pH Concentration of SO 2minus

4 (molL)

SC-1 ϕ660 0 SC-2 ϕ660 30 006 240 612SC-3 ϕ660 30 006 360 708SC-4 ϕ660 30 006 480 832SC-5 ϕ680 30 006 480 817SC-6 ϕ6100 30 006 480 843

Table 2 Mechanical properties of the concrete cubes

Number of spray cycles Cubic compressive strength (MPa)0 453240 451360 435480 403


7

65

9

9

4 3

8

12

11

12

1313

1010

9

Figure 4 Setup for the loading tests (1) Column specimen (2) reaction wall (3) hydraulic actuator (4) lateral load transfer assembly(5) hydraulic jack (6) sliding support (7) reaction beam (8) sensor (9) LVDTs (10) anchoring screws (11) foundation beam (12) strongfloor (13) gantry

(a) (b)

Figure 2 Photographs of the environmental chamber (a) Exterior (b) Interior

18 258 270 366 378 618 630 726 738

25

65

Spraying

Drying

Tem

pera

ture

(degC)

Time (min)

Each spray cycle took 360 min

Heating Cooling

Spraying

Drying

Heating Cooling

Figure 3 Corrosion scheme in the environmental chamber

Table 4 Loading protocol

Loading level Δ1 Δ2 Δ3 Δ4 Δ5 Δ6 Δ7 Δ8 Δ9 Δ10 Δ11 Δ12 Δ13 Δ14 Δ15 Δ16 Δ17 Δ18Displacement (mm) 03 06 09 12 15 18 24 33 39 45 50 65 80 100 130 160 190 220Number of cycles 1 1 1 1 1 1 1 3 3 3 3 3 3 3 3 3 3 3


Figure 5(d) e reason why is that corrosion products suchas CaSO4middot2H2O and Aft were continuously produced duringthis period Furthermore the dissolution of aggregates andthe decomposition of hydration products were more serious

e visual damage for the appearance characteristic ofcolumns SC-4 SC-5 and SC-6 was similar

32 Acidification Depth e acidification depth is the pen-etration depth in concrete material attack by acidic material insimulated acid rain solution [15 36 37]e acidification depthwas utilized in this paper to evaluate the acidification evolutionof the specimens subject to simulated acid rain exposure whichcharacterized the corrosion damage extent of the specimens

Table 1 summarizes the variation of acidification depth ofthe specimens over the number of spray cycles e acidifi-cation depth of the specimens increased nonlinearly with thenumber of spray cycles e acidification process can beapproximately divided into two stages namely initial growthperiod and stable growth period In the initial growth periodsince the cement hydration products were alkaline once theycontacted the acid solution the neutralization reaction oc-curred immediately e acidification rate was fast in thisperiod After 240 spray cycles the acidification depth of thespecimen was 612mmen in the stable growth period as aresult of the formation and expansion of corrosion products(such as CaSO4middot2H2O and Aft) the original pores in theconcrete were filled and the surface area of the specimenbecame dense e generated corrosion products acted as aprotective layer delaying the further acidification process ofacidic material to inside concrete of the specimen eacidification rate slowed down in this period After 360 and480 spray cycles the acidification depth of the specimenincreased to 708 and 817sim843mm respectively

33 Damage Process and Failure Mode e ultimate crackpatterns and failure morphologies of the six column spec-imens are shown in Figure 6 All column specimens were

dominated by similar flexural-shear failures under low cyclicreversed loads e typical failure process and damagecharacteristics are described as follows Before the longi-tudinal rebars yielded horizontal bending cracks were firstobserved at the column base Subsequently a few tinyvertical compression cracks which were visible to the nakedeye emerged along the longitudinal rebars at four corners ofthe column As the loading displacement amplitude in-creased the present vertical compression cracks continuedto extend upward e original horizontal bending cracksbroadened continuously and certain parts of these crackspropagated obliquely In addition a plurality of intersectingflexural-shear cracks gradually appeared at the bottom of thecolumn which indicated that the shearing effect was en-hanced in the column With the further increase in theloading displacement amplitude the longitudinal rebarsstarted to yield and the stirrups intersecting the flexural-shear cracks were approaching their tensile yieldingstrengths ereafter the number of diagonal cracks didnot increase further however the lengths and widths ofthese cracks continued to increase e concrete cover onthe frontage within 0sim200mm from the bottom of thecolumn was crushed in stages and increasingly peeled offe test ended when the remaining lateral load of thecolumn decreased to 85 of the peak load Eventually thedominant diagonal shear cracks with long and wide ex-tensions were formed in the lower part of the column atfailure A tortoise-shaped surface and a large spalled areawere observed on the concrete of the lower part of thecolumn and a portion of exposed steel bars was alsoobserved

e failure processes and damage characteristics of thecolumns showed a certain discrepancy due to the variationin the corrosion levels and stirrup ratios which could bediscussed as follows

(1) For columns SC-1 SC-2 SC-3 and SC-4 with thesame stirrup ratios as the level of corrosion in-creased the number of cracks in the lower parts of

(a) (b) (c) (d)

Figure 5 Visual damage of specimens under different levels of corrosion (a) SC-1 (0 cycles) (b) SC-2 (240 cycles) (c) SC-3 (360 cycles)(d) SC-4 (480 cycles)


the columns decreased whereas the crack spacingincreased and the crack width broadened ereason for these phenomena is that the corrosion ofthe steel bars weakened the bonding propertiesbetween the steel bars and the surrounding con-crete which led to the required transmission pathincreasing when a load of steel bars was transmittedto the concrete by means of the shear bond strengththereby increasing the crack spacing Moreover thecrack width is proportional to the crack spacingthus the crack width broadened by increasing thecrack spacing

(2) For columns SC-4 SC-5 and SC-6 with the samecorrosion levels as the stirrup ratio increasedX-shaped flexural-shear cracks in the plastichinge area of columns formed later and propa-gated more slowly is finding indicated that theshear failure characteristics of the columns

became less apparent at the end of the teststherefore the columns were less vulnerable toearthquake action

4 Experimental Results and Discussion

41CorrosionRatioof theSteelBar e corrosion of the steelbars in the plastic hinge area of an RC column is one of themain reasons for the deterioration of the seismic behaviourof the column erefore steel bars in the range of 300mmat the bottom of columns were marked during casting Afterthe loading tests ended the concrete covers in the plastichinge area of columns were first smashed and the longi-tudinal rebars and stirrups in the marked area were sepa-rately removed Hereafter the concrete and rust productsadhering to these removed steel bars were cleared After-ward the surfaces of these steel bars were cleaned withhydrochloric acid with a mass concentration of 12 and

(a) (b) (c)

(d) (e) (f )

Figure 6 Ultimate crack patterns and failure morphologies of the specimens (a) SC-1 (b) SC-2 (c) SC-3 (d) SC-4 (e) SC-5 (f ) SC-6


rinsed with water successively and then neutralized withlimestone Finally these steel bars were placed in an electricoven for approximately 4 hours to dry and then the barswere weighed by a balance e corrosion ratio which re-flects the actual corrosion condition of a steel bar is cal-culated as follows

η m1 minus m0

m0 (1)

where η is the actual corrosion ratio of the steel bar in termsof mass loss ratio m0 is the weight of a unit length of thenoncorroded steel bar and m1 is the weight of a unit lengthof the corroded steel bar after descaling

ere was still a certain degree of diversity in the actualmass loss ratios of these steel bars even under the samecorrosion level Consequently the average mass loss ratio ofthe longitudinal rebars and stirrups for each column wastaken as the actual corrosion ratio of the longitudinal rebarand stirrup respectively e calculation results are sum-marized in Table 5

ese results indicated that the corrosion ratios of thelongitudinal rebars and the corrosion ratios of the stirrupswere accelerated by increasing the corrosion level and therelationships were both approximately linear With the samenumber of spray cycles the corrosion ratio of a stirrup wassignificantly greater than that of a longitudinal rebar emain reasons for this phenomenon are illustrated as followsOn the one hand with the same corrosion depth the smallerthe diameter of a steel bar is the greater the calculatedcorrosion ratio is while the diameter of a stirrup in thecolumns was indeed smaller than that of a longitudinalrebar On the other hand the distance between the stirrupsand the outer surface of concrete is small When a corrosivemedium reached the surfaces of the stirrups and led tocorrosion the longitudinal rebars have not yet been affectedby the corrosive medium

42 Hysteresis Behaviour e hysteresis loop is the inter-relation of the lateral load and the top lateral displacementwhich can reflect the force state and deformation procedureof a specimen throughout the loading process Figure 7displays the hysteresis loops of the six column specimens

(1) e hysteresis loops of the specimens exhibited thefollowing analogous features Prior to the yieldingpoint the hysteresis loop was approximately linearand the loop was minuscule therefore there was nosignificant variation in the stiffness during loadingand unloading and there was almost no residualdeformation at the end of the unloading routes Asthe loading displacement amplitude increased thelongitudinal rebars in the specimens began to yieldand the form of the hysteresis loop translated fromapproximately linear to shuttle-shaped e stiffnessduring loading and unloading was degraded witheach subsequent stage the bearing capacity wassteadily improved and obvious residual deformationwas observed Moreover the area enclosed by thehysteresis loop expanded which showed evidence of

great energy dissipation for the specimens in thisstage After reaching the peak point the hysteresisloop exhibited a considerable pinching effect Si-multaneously the loop converted to an invertedS-shape and gradually reduced in size e stiffnessdegradation was further exacerbated due to theformation and expansion of inclined cracks in thelower parts of the specimens

(2) With respect to columns SC-1 SC-2 SC-3 and SC-4under the same stirrup ratios and different corrosionlevels during the initial stage of loading the hys-teresis loops varied linearly and the slopes of theloops decreased slightly as the corrosion level in-creased ereafter as the level of corrosion in-creased the platform segment near the peak pointbecame shorter Moreover the pinching effect of thehysteresis loops became increasingly obvious lead-ing to a progressive reduction in the fullness and areaof each loop at the same displacement-controlledloading level After the lateral load reached the peakvalue the greater the level of corrosion was the fasterthe slopes of the load-displacement curves reducedand the quicker the load-carrying capacities ofspecimens degraded

(3) With respect to columns SC-4 SC-5 and SC-6 underthe same corrosion levels and different stirrup ratiosbefore the lateral loading displacement reached thedisplacement value of the peak point the form of thehysteresis loop for column SC-4 was nearly the sameas those of SC-5 and SC-6 whereas the strengthattenuation and stiffness degradation of SC-4 wererelatively insubstantial at the same displacement-controlled loading level After the lateral loadingdisplacement reached the displacement value of thepeak point the rate of size reduction in the hysteresisloop for column SC-4 was less than those for SC-5and SC-6 indicating the stronger energy dissipationbehaviour of SC-4 Moreover the displacementcorresponding to the ultimate point of column SC-4was larger than those of SC-5 and SC-6 ie theductility of SC-4 was relatively better than that of theother columnsis phenomenon is because a higherstirrup ratio could effectively restrict the extension ofthe cracks and delay the buckling of the longitudinalrebars which provides excellent load-carrying anddeformation capacities to an RC column

43 Skeleton Curve Figure 8 shows the skeleton curves ofthe six column specimens which were designated as theaverages of the maximum absolute values of the load and

Table 5 Corrosion ratios of the steel bars

Specimen () SC-1 SC-2 SC-3 SC-4 SC-5 SC-6ηl 0 253 454 675 586 623ηs 0 532 813 1146 1277 1317Note ηl and ηs are the corrosion ratios of the longitudinal rebars andstirrups respectively


Longitudinal rebar yieldingStirrup yielding

Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150

ndash15 0 15 30ndash30Lateral displacement (mm)

(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )

Figure 7 Hysteresis loops of the specimens (a) SC-1 (b) SC-2 (c) SC-3 (d) SC-4 (e) SC-5 (f ) SC-6

Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160

ndash20 ndash10 0 10 20 30ndash30Lateral displacement (mm)

(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)

Figure 8 Skeleton curves of the specimens (a) Corrosion-level-induced changes (b) Stirrup-ratio-induced changes


displacement in the positive and negative directions for eachdisplacement-controlled loading level of hysteresis loops

Based on Figure 8 a number of commonalities in theskeleton curves can be discussed as follows In the initialstage of loading the skeleton curves exhibited approximatelylinear increases After reaching the yielding point the curvesbegan to bend which indicated that the growth rates of theload-carrying capacities for the specimens decreased whilethe damage to the specimens accumulated After the peakpoint the curves decreased at a rapid pace which meant theload-carrying capacities of the specimens were greatly re-duced In addition the positive and negative directions ofthe skeleton curves were not fully symmetrical which islikely due to three aspects (a) the nonsymmetry and dis-creteness of the corrosion characteristics on the surfaces ofsteel bars exposed to the artificial climate accelerated cor-rosion technique (b) the inevitable deviation during con-struction and the nonhomogeneity of the concrete materialand (c) the residual deformation that occurred during eachlevel of loading

Table 6 lists the characteristic parameters of the sixcolumn specimens e yielding points of the specimenswere determined by the equivalent energy method As il-lustrated in Figure 9 the area of the dashed region OAB isequal to that of the dashed region BCD the value at whichthe load of a column dropped to 85 of the peak load Ppwas defined as the ultimate load Pu Based on Figure 8 andTable 6 the following differences existed in the skeletoncurves of the specimens under various corrosion levels andstirrup ratios

(1) In reference to columns SC-1 SC-2 SC-3 and SC-4with the same stirrup ratios the loading processes ofthe noncorroded control specimen and corrodedspecimens were basically the same under the lowcyclic reversed load which could be categorized intothree stages elastic stage elastic-plastic stage andfailure stage Overall the skeleton curves of thecorroded specimens were lower than that of thecontrol specimen e decreases in the magnitudesof the yielding peak and ultimate loads from thecontrol specimen to the corroded specimens dis-played the same change rule each category of theseloads was positively correlated with the level ofcorrosion For instance the peak loads of columnsSC-2 SC-3 and SC-4 were 49 94 and 229 lessthan that of SC-1 respectively In the elastic stagethe skeleton curves of these four specimens sub-stantially overlapped In the elastic-plastic stage thedegradation in the load-carrying capacities andlateral stiffnesses of the corroded specimens wasmore obvious than that of the control specimen elengths of the platform segments in the corrodedspecimens were less than that of the control speci-men After entering the failure stage the skeletoncurves became increasingly steep as the corrosionlevel increased which indicated that the load-car-rying and deformation capacities of the corrodedspecimens compared to the control specimen were

more severely and more rapidly degraded Severalpossible causes exist for the deterioration in theseismic behaviours of the corroded RC columnspecimens which was described above In the firstinstance simulated acid rain resulted in the degra-dation of the mechanical properties of the concretematerial [6] Moreover compared with a non-corroded steel bar a corroded steel bar has a loweryield strength a shorter and less obvious yieldplatform and a reduced elongation limit [38] Lastlythe corrosion product of a steel bar expands involume which progressively increases the extrusionforce on the surrounding concrete causing theconcrete cover to crack bulge and peel off thisphenomenon reduces the bond strength and coop-erative working ability among the steel bar andsurrounding concrete ese findings illustrate thatthe impact of acid rain damage on the load-carryingcapacity of an RC column is noteworthy

(2) In reference to columns SC-4 SC-5 and SC-6 withthe same corrosion levels the yielding peak andultimate loads of the specimens were enhanced byincreasing the stirrup ratio As an example the peakloads of columns SC-4 and SC-5 were 113 and65 higher than that of SC-6 respectively In ad-dition as the stirrup ratio increased the length of theplatform segments of the skeleton curves corre-spondingly extended ie the occurrence of thefailure working stage was delayed in the specimensMoreover the descending branch after the peakpoints of curves became gentler us it can beinferred from the above phenomena that increasingthe stirrup ratio could fully exert the materialproperties of concrete in an RC column therebyefficaciously avoiding the abrupt occurrence ofcolumn failure

44 Deformation Capacity Table 6 shows the deformationparameters of six column specimens consisting of theyielding peak and ultimate displacements corresponding tothe yield peak and ultimate loads In addition the ductilitycoefficient (μ) and plastic deflection (θp) were adopted toassess the ductility variation in an RC column which is alsoprovided in Table 6 and can be represented as follows

μ Δu

Δy

θp Δu minus Δy

L

(2)

where Δy and Δu are the yielding and ultimate displace-ments respectively and L is the effective length of an RCcolumn specimen

(1) For columns SC-1 SC-2 SC-3 and SC-4 with thesame stirrup ratios as the corrosion level increasedvarious deformation parameters of the specimensexhibited downward trends Specifically as the


number of spray cycles increased from 0 to 480 theyielding displacement was reduced from 534 to472mm (116) the peak displacement was reducedfrom 959 to 821mm (144) and the ultimate dis-placement was reduced from 2060 to 1352mm(344) Furthermore as the corrosion level increaseda successive reduction was observed in the ductilitycoefficient and plastic deflection which illustrated thatthe deformation capacity of an RC column deterio-rated after acid rain exposure More adversely the factthat the ductility coefficient of columns SC-3 and SC-4ranged between 286 and 295 indicated that thesecolumns exhibited brittle failure modes

(2) For columns SC-4 SC-5 and SC-6 with the samecorrosion levels the yielding displacement exhibitedslight variations from 472 to 461mm which may bebecause the restraint effect provided by a higher stirrupratio on the specimens was not obvious during theelastic stage When the stirrup ratio was increasedfrom A6100 to A660 the peak displacement ul-timate displacement ductility coefficient and plasticdeflection of the specimens were gradually increasedthere was a 105 increase in the peak displacement325 increase in the ultimate displacement 355increase in the ductility coefficient and 636 increasein the plastic deflection It can be deduced that in-creasing the stirrup ratio has a beneficial effect on theductile deformation capacity of an RC column

45 StiffnessDegradation e secant stiffness Ki [25] is usedto characterize the stiffness values of the specimens which iscalculated according to the following equation

Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)

where +Pi and minusPi are the maximum load of the first cycleunder the i-th displacement-controlled loading level in thepositive and negative directions respectively and +Δi andminusΔi are the displacement values corresponding to +Pi andminusPi respectively

Based on test data the secant stiffness values of speci-mens versus the lateral displacements are calculated usingequation (3) and plotted in Figure 10 e observationsobtained are summarized as follows

(1) In terms of generality the stiffness values of thespecimens were originally high Subsequently it canbe observed that as the loading displacement am-plitude increased the slopes of the stiffness degra-dation curves were increased which meant that thestiffness values of specimens were rapidly degradeddue to the occurrence and extension of cracks Afterthe lateral loading displacement reached the dis-placement value of the peak point the rate ofstiffness degradation decreased and the curve tendedto flatten which might be ascribed to the formationof the dominant diagonal shear cracks in the spec-imens and the little effect of the generation of sec-ondary cracks on the stiffness

(2) With respect to columns SC-1 SC-2 SC-3 and SC-4with the same stirrup ratios and different corrosionlevels the initial stiffness values of the corrodedcolumns were slightly less than that of the non-corroded column e magnitude of stiffness degra-dation at the same displacement-controlled loadinglevel was increased by increasing the corrosion levelMoreover as the loading displacement amplitudeincreased the rate of reduction in the stiffness valuesof the specimens increased with increasing corrosionlevels As shown in Figure 10(a) the curve of columnSC-4 had the fastest decreasing rate ese resultsshowed that acid rain has a substantial influence onthe stiffness of an RC column

(3) With respect to columns SC-4 SC-5 and SC-6 withthe same corrosion levels and different stirrup ratiosthe initial stiffness values of columns SC-4 and SC-5were 115 and 62 greater than that of SC-6 at thehigher stirrup ratio As the loading displacementamplitude increased the degree of degradation in the

Table 6 Main seismic performance parameters of the specimens

SpecimenYielding point Peak point Ultimate point

Ductility coefficient μ Plastic deflection θp(rad)Py (kN) Δy (mm) Pp (kN) Δp (mm) Pu (kN) Δu (mm)

SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp

Figure 9 Definition of the yielding point


stiffness values of columns SC-4 and SC-5 was rel-atively less severe than that of SC-6 ie the stiffnessof a specimen with a higher stirrup ratio wasmarkedly greater than that of a specimen with alower stirrup ratio at the same displacement-con-trolled loading level is finding shows that in-creasing the stirrup ratio could improve theresistance-deformation capacity of an RC column tosome extent

46 Energy Dissipation Behaviour In the seismic design ofan RC structure it is required that the structure and itsinternal components should have a sufficient energy dissi-pation capacity so that the structure can consume a sub-stantial amount of seismic energy when subjected to anearthquake without being damaged or immediately col-lapsing e cumulative hysteretic dissipation energy E [39]and equivalent viscous damping coefficient he [40 41] areused to evaluate the energy dissipation capacities of thespecimens subjected to simulated acid rain exposure

461 Equivalent Viscous Damping Coefficient e equiv-alent viscous damping coefficient can be computed from thefollowing equation

he 12π

SABCD

SΔOBE + SΔOAD

(4)

where SABC D is the measured area of the hysteresis loopABCD and SΔOBE and SΔOA D are the idealized elastic-plasticareas of triangle OBE and OAD respectively as shown inFigure 11

e equivalent viscous damping coefficients hey hep andheu which correspond to yielding peak and ultimate pointsof the specimens respectively are summarized in Table 7 As

shown (1) with the progression of the loading process in allthe specimens the equivalent viscous damping coefficientsgradually increased indicating that the energy dissipationcapacities of specimens were gradually exerted For columnsSC-1 and SC-6 from the yielding points to ultimate pointsthe equivalent viscous damping coefficients were increasedfrom 00556 and 00375 to 01809 and 01205 respectively(2) A comparison was made among the specimens with the

0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)

5 10 15 20 250Lateral displacement (mm)

SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)

Figure 10 Stiffness degradation curves of the specimens (a) Corrosion-level-induced changes (b) Stirrup-ratio-induced changes

O C E

B

AF

D

Lateral force

Lateral displacement

Figure 11 Calculation diagram of the equivalent viscous dampingcoefficient

Table 7 Hysteretic energy dissipation indicators of the specimens

Specimen hey hep heu Emiddot(kNmiddotmm)SC-1 00556 00989 01809 1196050SC-2 00517 00879 01529 1057748SC-3 00495 00850 01517 933855SC-4 00425 00814 01462 791472SC-5 00423 00679 01276 702547SC-6 00375 00668 01205 647338Note E is the cumulative hysteretic dissipation energy under the thirty-second displacement-controlled loading cycles for easing of comparisonand the total number of loading cycles for the six specimens in Figure 12 isdiverse


same stirrup ratios (columns SC-1 SC-2 SC-3 and SC-4)e equivalent viscous damping coefficients hey hep andheu of the specimens decreased monotonically from 0055600989 and 01809 to 00425 00814 and 01462 as the levelof corrosion increased (3) A comparison among specimenswith the same corrosion levels (columns SC-4 SC-5 andSC-6) was also made As the stirrup ratio increased theequivalent viscous damping coefficients hey hep and heu

increased continuously e equivalent viscous dampingcoefficients heu of columns SC-4 and SC-5 were 213 and59 greater than that of SC-6 respectively e abovephenomenon showed that the variations in both the cor-rosion level and stirrup ratio would have significant in-fluences on the fullness of the hysteresis loops of thespecimens

462 Cumulative Hysteretic Dissipation Energy One im-portant indicator for quantifying the energy dissipationcapacity of an RC column specimen is the cumulativehysteretic dissipation energy which is the total energy valueaccumulated under the low cyclic reversed loading test andcan be calculated from the following equation

E 1113944n

j1Ej (5)

where Ej is the hysteretic dissipation energy under the j-thdisplacement-controlled loading cycle and calculated bythe measured area of the hysteresis loop ABCD as shownin Figure 11 and n is the total number of loading cyclesFigure 12 presents the curves of the cumulative hystereticdissipation energy of the six column specimens as a

function of the displacement-controlled loading cyclese cumulative hysteretic dissipation energy calculationresults for all the specimens are listed in Table 7

As shown in Figure 12 and Table 7 the cumulativehysteretic dissipation energy values of the specimens wererelated to three parameters namely displacement-con-trolled loading cycle corrosion level and stirrup ratio asspecifically described below (1) As the displacement-controlled loading cycle increased the total dissipatedenergy values of all specimens increased monotonicallyduring the loading tests (2) In reference to columns SC-1SC-2 SC-3 and SC-4 with the same stirrup ratios obviousreductions were observed in the cumulative hystereticdissipation energy of specimens subjected to simulated acidrain exposure and the magnitudes of these reductions wereincreased by increasing the corrosion level e cumulativeenergy values of the corroded columns SC-2 SC-3 and SC-4 were 115 219 and 338 less than that of the controlcolumn SC-1 respectively Moreover as the number ofdisplacement-controlled loading cycles increased the dif-ference in the cumulative hysteretic dissipation energyvalues between the noncorroded and corroded specimensgradually increased is finding suggests that the energydissipation capacity of an RC column is substantially af-fected by the corrosion level (3) In reference to columnsSC-4 SC-5 and SC-6 with the same corrosion levels thecumulative hysteretic dissipation energy values of thespecimens were increased in stages as the stirrup ratioincreased e cumulative energy values of columns SC-4and SC-5 significantly increased these values were 223and 85 greater than that of SC-6 respectively isfinding indicates that increasing the stirrup ratio can en-hance the energy dissipation capacity of an RC column

0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)

10 20 30 400Displacement-controlled loading cycle (no)

SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)

Figure 12 Cumulative hysteretic dissipation energy curves of the specimens (a) Corrosion-level-induced changes (b) Stirrup-ratio-induced changes


5 Conclusions

is paper conducted a sequence of artificial climate acceleratedcorrosion tests and low cyclic reversed loading tests on six RCcolumn specimens e influences of the corrosion level andstirrup ratio on the visual damage failure mode and variousseismic behaviour indexes of the columns were systematicallyinvestigated On the basis of the primary test results the fol-lowing conclusions can be drawn

(1) e appearance characteristics of the six columnspecimens exhibited varying degrees of visual damagefrom the simulated acid rain exposure e greater thelevel of corrosion the more severe the visual damage ofthe specimens For column SC-4 which was subjectedto 480 spray cycles the surface became rough andpitted some of the coarse aggregates were exposed andthe concrete texture loosened

(2) All six column specimens were dominated by analogousflexural-shear failures under the low cyclic reversedloads despite the distinctions in corrosion level andstirrup ratio Nevertheless there were some variations inthe damage processes of the specimens with differentcorrosion levels and stirrup ratiosWith increasing levelsof corrosion the number of cracks in the lower parts ofthe columns decreased whereas the crack spacing in-creased and the crack width broadened As the stirrupratio increased X-shaped flexural-shear cracks in theplastic hinge areas of the columns occurred later in theloading process and the propagation speed of thesecracks was slower Furthermore the pinching effect ofthe hysteresis loops became increasingly obvious

(3) In regard to the specimens with the same stirrupratios as the corrosion level increased the load-carrying capacities deformation capacities stiff-nesses and energy dissipation capacities of thespecimens were continuously decreased Comparedwith the control column SC-1 the peak load duc-tility coefficient and cumulative hysteretic dissipa-tion energy of the highly corroded column SC-4decreased by 229 259 and 338 respectively

(4) Regarding the specimens with the same corrosionlevels the higher the stirrup ratio the stronger therestraint effect of the stirrups on the concrete andthe seismic behaviours of the specimens were ob-viously improved e peak load ductility coeffi-cient initial stiffness and cumulative hystereticdissipation energy of column SC-4 were 113 355115 and 223 greater than those of SC-6

Data Availability

e data used to support the findings of this paper areavailable from the corresponding author upon request

Conflicts of Interest

e authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

is work was supported by the National Science and Tech-nology Support Program (no2013BAJ08B03) and the ResearchFund of Shaanxi Province in China (no2017ZDXM-SF-093)

References

[1] Y-Z Cao S Wang G Zhang J Luo and S Lu ldquoChemicalcharacteristics of wet precipitation at an urban site ofGuangzhou South Chinardquo Atmospheric Research vol 94no 3 pp 462ndash469 2009

[2] P C Mouli S V Mohan and S J Reddy ldquoRainwaterchemistry at a regional representative urban site influence ofterrestrial sources on ionic compositionrdquo Atmospheric En-vironment vol 39 no 6 pp 999ndash1008 2005

[3] F C Menz and H M Seip ldquoAcid rain in Europe and theUnited States an updaterdquo Environmental Science amp Policyvol 7 no 4 pp 253ndash265 2004

[4] D-J Ling Q-C Huang and Y Ouyang ldquoImpacts of sim-ulated acid rain on soil enzyme activities in a latosolrdquo Eco-toxicology and Environmental Safety vol 73 no 8pp 1914ndash1918 2010

[5] Y Lv C Wang Y Jia et al ldquoEffects of sulfuric nitric andmixed acid rain on litter decomposition soil microbial bio-mass and enzyme activities in subtropical forests of ChinardquoApplied Soil Ecology vol 79 pp 1ndash9 2014

[6] Y F Fan Z Q Hu Y Z Zhang and J L Liu ldquoDeteriorationof compressive property of concrete under simulated acid rainenvironmentrdquo Construction and Building Materials vol 24no 10 pp 1975ndash1983 2010

[7] V Zivica and A Bajza ldquoAcidic attack of cement based ma-terials-a review part 1 Principle of acidic attackrdquo Con-struction and Building Materials vol 15 no 8 pp 331ndash3402001

[8] Y Y Guan and S S Zheng ldquoSeismic behaviors of RC framebeam-column joints under acid rain circle a pilot experi-mental studyrdquo Journal of Earthquake Engineering vol 6no 22 pp 1ndash19 2017

[9] J Hill E A Byars J H Sharp C J Lynsdale J C Cripps andQ Zhou ldquoAn experimental study of combined acid andsulfate attack of concreterdquo Cement and Concrete Compositesvol 25 no 8 pp 997ndash1003 2003

[10] M Gregerova and D Vsiansky ldquoIdentification of concretedeteriorating minerals by polarizing and scanning electronmicroscopyrdquo Materials Characterization vol 60 no 7pp 680ndash685 2009

[11] S Xie L Qi and D Zhou ldquoInvestigation of the effects of acidrain on the deterioration of cement concrete using acceleratedtests established in laboratoryrdquo Atmospheric Environmentvol 38 no 27 pp 4457ndash4466 2004

[12] M-C Chen K Wang and L Xie ldquoDeterioration mechanismof cementitious materials under acid rain attackrdquo EngineeringFailure Analysis vol 27 pp 272ndash285 2013

[13] H Okochi H Kameda S-I Hasegawa N Saito K Kubotaand M Igawa ldquoDeterioration of concrete structures by aciddeposition-an assessment of the role of rainwater on dete-rioration by laboratory and field exposure experiments usingmortar specimensrdquo Atmospheric Environment vol 34 no 18pp 2937ndash2945 2000

[14] X X Zha and J K Lu ldquoStudy of durability of recycledconcrete under the environment of the acid rainrdquo AppliedMechanics and Materials vol 71ndash78 pp 5042ndash5045 2011


[15] Z Wang Z Zhu X Sun and X Wang ldquoDeterioration offracture toughness of concrete under acid rain environmentrdquoEngineering Failure Analysis vol 77 pp 76ndash84 2017

[16] C Zhou Z Zhu Z Wang and H Qiu ldquoDeterioration ofconcrete fracture toughness and elastic modulus undersimulated acid-sulfate environmentrdquo Construction andBuilding Materials vol 176 pp 490ndash499 2018

[17] Y F Fan D W Wang and H Y Luan ldquoStudy on the loadcarrying capacity of reinforced concrete beams under acidprecipitationrdquo Engineering Mechanics vol 31 no 4pp 147ndash154 2014 in Chinese

[18] A C Lynn J P Moehle S A Mahin and W T HolmesldquoSeismic evaluation of existing reinforced concrete buildingcolumnsrdquo Earthquake Spectra vol 12 no 4 pp 715ndash7391996

[19] N S Vu and B Li ldquoSeismic performance assessment ofcorroded reinforced concrete short columnsrdquo Journal ofStructural Engineering vol 144 no 4 Article ID 040180182018

[20] Y Ma Y Che and J Gong ldquoBehavior of corrosion damagedcircular reinforced concrete columns under cyclic loadingrdquoConstruction and Building Materials vol 29 pp 548ndash5562012

[21] D Li R Wei F Xing L Sui Y Zhou and W Wang ldquoIn-fluence of non-uniform corrosion of steel bars on the seismicbehavior of reinforced concrete columnsrdquo Construction andBuilding Materials vol 167 pp 20ndash32 2018

[22] A Meda S Mostosi Z Rinaldi and P Riva ldquoExperimentalevaluation of the corrosion influence on the cyclic behaviourof RC columnsrdquo Engineering Structures vol 76 pp 112ndash1232014

[23] Q Li D-T Niu Q-H Xiao X Guan and S-J ChenldquoExperimental study on seismic behaviors of concrete col-umns confined by corroded stirrups and lateral strengthpredictionrdquo Construction and Building Materials vol 162pp 704ndash713 2018

[24] S-Y Yang X-B Song H-X Jia X Chen and X-L LiuldquoExperimental research on hysteretic behaviors of corrodedreinforced concrete columns with different maximumamounts of corrosion of rebarrdquo Construction and BuildingMaterials vol 121 pp 319ndash327 2016

[25] JGJ 101-96 Specificating of Testing Methods for EarthquakeResistant Building China Architecture amp Building PressBeijing China 1996 in Chinese

[26] GB 50010-2010 Code for Design of Concrete Structures ChinaArchitecture amp Building Press Beijing China 2010 inChinese

[27] GB 50011-2010 Code for Seismic Design of Buildings ChinaArchitecture amp Building Press Beijing China 2010 inChinese

[28] W Yang S-S Zheng D-Y Zhang L-F Sun and C-L GanldquoSeismic behaviors of squat reinforced concrete shear wallsunder freeze-thaw cycles a pilot experimental studyrdquo Engi-neering Structures vol 124 pp 49ndash63 2016

[29] Q Qin S Zheng L Li L Dong Y Zhang and S DingldquoExperimental study and numerical simulation of seismicbehavior for RC columns subjected to freeze-thaw cyclesrdquoAdvances in Materials Science and Engineering vol 2017Article ID 7496345 13 pages 2017

[30] S Xu A Li Z Ji and Y Wang ldquoSeismic performance ofreinforced concrete columns after freeze-thaw cyclesrdquo Con-struction and Building Materials vol 102 pp 861ndash871 2016

[31] Bulletin of the State of the Environment of China 2016 httpwwwmeegovcnhjzl

[32] H B Hu ldquoAnalysis for simulation test on acid rain attackingconcreterdquo Journal of the Chinese Ceramic Society vol 36no S1 pp 147ndash152 2008 in Chinese

[33] S D Xie D Zhou Q X Yue and H L Liu ldquoStudy ofsimulated acid rain on concreterdquo Environmental Sciencevol 16 no 5 pp 22ndash26 1995 in Chinese

[34] Q Q Zhang Y Yan Z F Wang and X N Dong ldquoPre-cipitation characteristics in chongqing during 1961ndash2012rdquoJournal of Nanjing University of Information Science ampTechnology (Natural Science Edition) vol 8 no 3 pp 215ndash225 2016 in Chinese

[35] T Paulay and M J N Priestley Seismic Design of ReinforcedConcrete and Masonry Buildings pp 140ndash142 John Wiley ampSons Hoboken NJ USA 1992

[36] J G Niu H T Zhai and D T Niu ldquoInvestigation onneutralization rules of concrete under loads subjected to acidrain attackrdquo Advanced Materials Research vol 243ndash249pp 5768ndash5771 2011

[37] B Li L Cai and W Zhu ldquoPredicting service life of concretestructure exposed to sulfuric acid environment by grey systemtheoryrdquo International Journal of Civil Engineering vol 16no 9 pp 1017ndash1027 2018

[38] Q Wu and Y S Yuan ldquoExperimental study on the deteri-oration of mechanical properties of corroded steel barsrdquoChina Civil Engineering Journal vol 41 no 12 pp 42ndash472008 in Chinese

[39] C Qian Y Li D Xie N Li and X Wen ldquoSeismic perfor-mance experiment involving one-story two-bay self-controlenergy dissipation UPPC frames under low cyclic loadsrdquo KsceJournal of Civil Engineering vol 23 no 7 pp 3041ndash30482019

[40] Z Zhu and Z Guo ldquoSeismic behavior of precast concreteshear walls with different confined boundary elementsrdquo KsceJournal of Civil Engineering vol 23 no 2 pp 711ndash718 2019

[41] H Zhang H Liu G Li and X Ning ldquoSeismic performance ofencased steel plate-reinforced gangue concrete compositeshear wallsrdquo Ksce Journal of Civil Engineering vol 23 no 7pp 2919ndash2932 2019


essentially caused by the accumulation of microscopicdamage Xie et al [11] carried out an accelerated corrosiontest by using a mixed solution of sulfuric acid nitric acidand ammonium sulfate to simulate the various deteriorationstages of cement concrete specimens during acid rain ex-posure e corrosion of concrete by a simulated acid rainsolution was divided into three stages the neutralizationdepth of specimens can be expressed as a function of thecorrosion time and the deterioration of material propertiesof specimens was caused by H+ dissolution damage andSO 2minus

4 expansion damage Chen et al [12] also noted that thedegradation of the mechanical properties of concrete ce-mentitious specimens subjected to simulated acid rain ex-posure resulted from the coupled effect of H+ and SO 2minus

4 andthe deterioration accumulated from the outside to the insideof the specimens Okochi et al [13] experimented with theinfluence of acid deposition on a concrete structure by usingan indoor spray test and a field exposure test eir resultsshowed that the higher the concentration of H+ andSO 2minus

4 was the more severely the concrete was corroded Fanet al [6] conducted a range of tests on 354 concrete prismaticsamples with dimensions of 150mmtimes 150mmtimes 300mmUltrasonic testing technology was a reliable method for thenondestructive measurement of damage depth and thedamage index corresponding to the change in the relativecompressive strength was more suitable for characterizingthe deterioration state of concrete exposed to acid rain Zhaand Lu [14] investigated the differentiae on account ofexperimental research in the compressive strengths of or-dinary Portland concrete and recycled concrete under ar-tificial acid rain exposure Under the action of a simulatedacid rain exposure significant variations occurred in thephysical and chemical properties of the concrete materialresulting in a corresponding reduction in fracture toughnessand elastic modulus and the lower the pH value the fasterthe degradation rate [15 16]

Conclusively the deterioration of the mechanicalproperties of concrete caused by acid rain exposure has beenfully studied On the component level acid rain exposurenot only influences the mechanical properties of concretebut also corrodes the internal steel bars Less attention hasbeen devoted to the variations in the mechanical propertiesof RC components subjected to acid rain exposure Guanand Zheng [8] employed an artificial climate simulationtechnology to study the effect of acid rain on the seismicbehaviours of interior beam-column joints with differentaxial compression ratios An artificial rainfall device wasdesigned by Fan et al [17] to simulate real acid rain and theflexural behaviours of RC beams operating in an acid rainenvironment were investigated Hence the surface mor-phology and mechanical properties of RC components weresignificantly affected by acid rain

RC columns are the main load-carrying components inan RC structure wherein the columns carry the loads frombeams and slabs and further transfer the loads to thefoundation [18] If some columns failed during an earth-quake the reliability of the whole structure would be greatlyadversely affected An RC column component under an acidrain environment is subjected to the corrosive media of

carbon dioxide sulfate ions and nitrate ions As a result theoverall mechanical properties and seismic behaviours of anRC column component are constantly deteriorated each daywhich gravely threatens the reliability of an in-service RCbuilding structure However for RC columns the existingresearch has focused only on the effects of steel bar corrosionon the behaviours of RC columns Based on simulatedseismic loading tests of eight full-size corroded RC shortcolumns Vu and Li [19] found that the shear strengths anddeformation capacities of corroded columns were markedlylower than those of noncorroded columns particularlyunder high corrosion levels and high axial compressionratios Moreover methods considering the influence ofstirrup corrosion for evaluating the shear strength of shortconcrete columns were proposed Ma et al [20] conductedquasistatic loading tests on thirteen circular RC columnsthat had been subjected to accelerated corrosion tests Onthe strength of the test results degradationmodels of seismicperformance indicators involving the strengths and ductil-ities of columns were presented Li et al [21] analysed theimpact of nonuniform steel bar corrosion on the seismicperformance of RC columns Under the influence of non-uniform steel bar corrosion the seismic performance of RCcolumns after peak points was dramatically diverse in thepositive and negative loading directions In the experimentalstudy performed by Meda et al [22] it was reported that theload-bearing and deformation capacities of RC columnsunder cyclic loading were substantially influenced by thecorrosion of the reinforcement Li et al [23] experimentedwith the cyclic behaviours of eight RC columns with cor-roded stirrups eir results showed that the bearing ca-pacities of columns increased slightly at the outset when thecorrosion ratios of the stirrups were less and then decreasedas the corrosion ratio increased further Yang et al [24]investigated the bending capacities of corroded RC columnswhich simulated a marine environment e hystereticbehaviours of columns deteriorated as the corrosion levelincreased For example when the maximum mass loss ratioof the reinforcing bars reached 168 the bending strengthand ductility coefficient of the corroded column were re-duced by 20 and 321 respectively compared with thoseof the column without corrosion In the above analyseselectrochemical methods were adopted to accelerate thecorrosion processes of steel bars in RC columns and manyachievements were made Nevertheless as far as the authorsknow the study on the seismic behaviours of RC columnscorroded by such corrosive media as carbon dioxide sulfateions and nitrate ions in an acid rain environment has notbeen reported to date

In view of the above accounts this paper aims to ex-perimentally study the influence of the corrosion levelwhich is regulated by an artificial climate accelerated cor-rosion technique on the seismic behaviours of RC columnsunder an acid rain environment In this test six RC columnspecimens were fabricated with different corrosion levelsand stirrup ratios and the columns were subjected to lowcyclic reversed loads e test outcomes are conducive to theevaluation of seismic behaviours for RC structures damagedby acid rain






















Diameter(mm)



Elasticmodulus(MPa)

ϕ6 305 440 21times 105

ϕ16 373 537 20times105

ϕ6

30

100

400

400

200

ϕ6

608

010

0

2 2

ϕ6

100

1

1


422

422

400

1-1

400

222

316

200

2-2

200

316





4 (molL)





7

65

9

9

4 3

8

12

11

12

1313

1010

9


(a) (b)


18 258 270 366 378 618 630 726 738

25

65

Spraying

Drying

Tem

pera

ture

(degC)

Time (min)


Heating Cooling

Spraying

Drying

Heating Cooling













(a) (b) (c) (d)








(a) (b) (c)

(d) (e) (f )




η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References
































































Diameter(mm)



Elasticmodulus(MPa)

ϕ6 305 440 21times 105

ϕ16 373 537 20times105

ϕ6

30

100

400

400

200

ϕ6

608

010

0

2 2

ϕ6

100

1

1


422

422

400

1-1

400

222

316

200

2-2

200

316





4 (molL)





7

65

9

9

4 3

8

12

11

12

1313

1010

9


(a) (b)


18 258 270 366 378 618 630 726 738

25

65

Spraying

Drying

Tem

pera

ture

(degC)

Time (min)


Heating Cooling

Spraying

Drying

Heating Cooling













(a) (b) (c) (d)








(a) (b) (c)

(d) (e) (f )




η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References




















































Diameter(mm)



Elasticmodulus(MPa)

ϕ6 305 440 21times 105

ϕ16 373 537 20times105

ϕ6

30

100

400

400

200

ϕ6

608

010

0

2 2

ϕ6

100

1

1


422

422

400

1-1

400

222

316

200

2-2

200

316





4 (molL)





7

65

9

9

4 3

8

12

11

12

1313

1010

9


(a) (b)


18 258 270 366 378 618 630 726 738

25

65

Spraying

Drying

Tem

pera

ture

(degC)

Time (min)


Heating Cooling

Spraying

Drying

Heating Cooling













(a) (b) (c) (d)








(a) (b) (c)

(d) (e) (f )




η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References












































7

65

9

9

4 3

8

12

11

12

1313

1010

9


(a) (b)


18 258 270 366 378 618 630 726 738

25

65

Spraying

Drying

Tem

pera

ture

(degC)

Time (min)


Heating Cooling

Spraying

Drying

Heating Cooling













(a) (b) (c) (d)








(a) (b) (c)

(d) (e) (f )




η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References




















































(a) (b) (c) (d)








(a) (b) (c)

(d) (e) (f )




η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References

















































(a) (b) (c)

(d) (e) (f )




η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References













































η m1 minus m0

m0 (1)














Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References













































Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(a)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(b)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(c)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(d)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(e)


Late

ral l

oad

(kN

)

ndash150

ndash100

ndash50

0

50

100

150


(f )


Late

ral l

oad

(kN

)

SC-1SC-2

SC-3SC-4

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(a)

SC-4SC-5SC-6

Late

ral l

oad

(kN

)

ndash160

ndash120

ndash80

ndash40

0

40

80

120

160


(b)










μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References



















































μ Δu

Δy

θp Δu minus Δy

L

(2)







Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References















































Ki +Pi

11138681113868111386811138681113868111386811138681113868 + minusPi

11138681113868111386811138681113868111386811138681113868

+Δi

11138681113868111386811138681113868111386811138681113868 + minusΔi

11138681113868111386811138681113868111386811138681113868 (3)









SC-1 12233 534 14553 959 12370 2060 386 031SC-2 11611 503 13837 912 11761 1592 317 022SC-3 11353 476 13189 873 11211 1402 295 019SC-4 9570 472 11222 821 9539 1352 286 018SC-5 8904 470 10563 770 8979 1309 278 017SC-6 8526 461 10084 743 8571 1020 221 011

P

0

B

C

A

Y

D

ΔΔy

PpPy

Δp






he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References















































he 12π

SABCD

SΔOBE + SΔOAD

(4)




0

20

40

60St

iffne

ss (k

Nmiddotm

mndash1

)


SC-1SC-2

SC-3SC-4

(a)

0

20

40

60

Stiff

ness

(kN

middotmm

ndash1)


SC-4SC-5SC-6

(b)


O C E

B

AF

D

Lateral force









E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References















































E 1113944n

j1Ej (5)




0

10

20

30Cu

mul

ativ

e hys

tere

ticdi

ssip

atio

n en

ergy

(kN

middotm)


SC-1SC-2

SC-3SC-4

(a)

0

5

10

15

Cum

ulat

ive h

yste

retic

diss

ipat

ion

ener

gy (k

Nmiddotm

)


SC-4SC-5SC-6

(b)



5 Conclusions






Data Availability




Acknowledgments


References












































5 Conclusions






Data Availability




Acknowledgments


References








































































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