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Civil Engineering Program
CVE 400
SUMMER PRACTICE REPORT
Name of Student : ALİ CAN OKUR
ID Number : 1728955
Name of Company : İNPRO Mühendislik Müşavirlik
İnş. San. ve Tic. Ltd. Şti.
Date of Submission : 19.10.2015
TABLE OF CONTENTS
1. INTRODUCTION........................................................................................................................4
2. IFORMATION ABOUT THE COMPANY:..............................................................................4
3. STEPS OF BRIDGE DESIGN:..................................................................................................5
3.1. Material Selection:................................................................................................................5
3.2. Modeling Stage :..................................................................................................................6
3.3. Structural Analysis :...........................................................................................................12
3.4. Final Design :......................................................................................................................23
4. CONCLUSION :.........................................................................................................................25
LIST OF FIGURES
Figure 1. Material selection........................................................................................................6
Figure 2 Abutment Structure at Auto-CAD environment..........................................................6
Figure 3. Dimensions of an Abutment........................................................................................7
figure 4. Finished bridge structure..............................................................................................8
figure 5. Elevation view of abutment..........................................................................................8
figure 6 Pile Information.............................................................................................................8
Figure 7. Area Sections...............................................................................................................9
Figure 8. An abutment structure with pile foundation..............................................................11
Figure 9.Dimension and unit weight information.....................................................................13
Figure 10.Dead load Calculations.............................................................................................13
Figure 11.Force Assigning process...........................................................................................14
Figure 12. Dead Load locations................................................................................................15
Figure 13. Joint Load assigning................................................................................................16
Figure 14. Area load assigning.................................................................................................17
Figure 15. Load patterns defined on SAP2000.........................................................................18
Figure 16. Displacement and rotation values............................................................................19
Figure 17. Shear force and moment heat maps for foundation.................................................20
Figure 18. Shear force and moment heat maps for structural wall...........................................20
Figure 19. Shear force diagram for piles and girder flange......................................................21
Figure 20. Moment diagram for piles and girder flange...........................................................21
Figure 21. Analysis results on MS. Excel sheet........................................................................22
Figure 22. Reinforcement calculations 1..................................................................................23
Figure 23. Reinforcement calculations 2..................................................................................24
Figure 24. Reinforcement calculations 3..................................................................................25
1. INTRODUCTION
After completing CVE 300 summer practice at the construction site, the aim of this summer
practice, which is CVE 400, is to gain knowledge and experience in design office.
After some research I decided to perform my summer practice in INPRO Engineering and
Consultancy Company to learn how I can use my theoretical knowledge in pratic.
I started my summer practice on August 17 and finished on September 11.During my
summer practice I worked with the bridge department of the company and tried to understand
the steps and important points about the design of a bridge structure. Throughout the summer
practice I used AUTO-CAD, SAP2000 and some excel sheet that are prepared by the
engineers in the company. I tried to understand the basic of the specifications of Turkish
General Directorate of Highways and AASHTO.
In this report, I tried to transfer my observations, impressions and knowledge about a design
office and design steps of construction project that I learn from my summer practice.
2. IFORMATION ABOUT THE COMPANY:
INPRO Engineering and Consultancy is a design company that generally provides
engineering and consultancy services for transportation, infrastructure and industrial projects.
The company was established in 2003 and since then they completed over 250 bridge
projects, 450 km roadway projects, 35 level crossing structures and 140 level crossing
projects. As far as I observed, the company has 2 main departments: bridge and roadway
departments. During my summer practice, I worked with the bridge department, which consist
of 10 civil engineers and four technicians.
3. STEPS OF BRIDGE DESIGN:
During my summer practice, I worked on abutment structures. Design steps of an
abutment structure can be listed as:
Material selection
Modeling stage
Structural analysis
Final design
All stages of the design are done according to the codes listed below.
AASHTO – Standard specifications for highway bridges
ACI – American reinforced concrete specification
TS 500 – Turkish reinforced concrete specification
TS 3233 –Turkish pre-stressed concrete specification
DIN 1072 – German bridge loads specification
DIN 1075- German bridge specification
DIN 4227- German pre-stressed concrete specification
3.1. Material Selection:
In every construction process, one of the most important stages is determining the correct
material for the project needs, which have to be strong, durable and also economical. Material
selection is done according to the Turkish, American and German specifications. Concrete
grade has to be BS20 (C20) or BS25 (C25), reinforcing steel grade has to be S220 or S420,
and pre-stressed concrete grade has to be BS40 (C40), BS45 (C45) or BS50 (C50).
Figure 1. Material selection
3.2. Modeling Stage :
At that stage of the design process aim is to create a virtual model for that specific part
according to the drawings. Most important part at the modeling stage is try to reflect the site
conditions as much as possible to the real case.
For modeling Stage Auto-CAD and SAP2000 environments are used. Dimensions of the
abutment structures are taken from Auto-CAD file and a virtual abutment structure was
created at the SAP 2000 environment.
Figure.
Abutment Structure at Auto-CAD environment
There are two abutment structures at the both side of the road that cross pass the bridge .By
using the tools in Auto-CAD the dimensions of the structure is determined .(Fig.2.)
From Fig.3. an abutment structure in roughly U shape structure the yellow lines represent the
margin lines for the bridge structure .Yellow lines shows the margin for road and the outer
yellow lines shows the sidewalks. Light blue lines shows the abutment structure . Structure
shown in Fig.3. has a pile foundations and piles are shown with the orange lines . Locations of
piles are determined and indicated whit the green lines . First stage of modeling is to read all
this details from Auto-CAD file and transfer it to the SAP2000 environment.
The main function of abutment structure is they act like a support for the bridge structure
above them, for this abutment it has a pile foundation and this determined after the
geotechnical investigation of the soil by standard or cone penetration test . Also type and size
of abutment structure is also important for determination of the foundation of the abutment.
Figure 3. Dimensions of an Abutment
Figure 4. Finished bridge structure
Fig.4. shows a complete version of a bridge structure and span of the bridge is made by using
pre-stressed concrete beams which are stay above the abutments that are located two sides of
the roads. Also after abutment is finished the inner parts of the structure is filled with soil and
the pressure of soil will be also calculating at the structural analysis stage.
By the help of the elevation view in Fig.5. We can determine the height of the structure for
modeling. Inspection of Fig.5. Is important because this figure shows the elevation of
different part of abutment structure like foundation , elevation (elevasyon) and shield(kalkan)
which are different parts of the structure . For the abutment structure in Fig.5. Has mat
foundation when pile foundation or mixed foundation is used length of the piles also be
determined from the Auto-CAD files. From Fig.6. On the right side detailed pile information.
Figure 5. Elevation view of abutment
After all dimensions are determined from the Auto-CAD files, virtual copy of the structure
can be created at the SAP2000 environment. When virtual copy was created to get better
results from the software , abutment structure represented as 0.5 -0.5(m) square shell
elements . By assembling those shell elements whole abutment structure is tried to virtually
created. Another important point while abutment structure was created is that; shell elements
was assembled trough the centerlines of the walls of the structure, it is important because,
when you get dimensions from the Auto-CAD file you need to pay attention to the centerline
dimensions.
Figure 7. Area Sections
From Fig.7. There are several different sections defined for different parts of the structure.
Since different parts has different section properties proper sections needs to be selected for
shell elements on the structure . From Fig.7.there are 8 different section options for this
abutment structure. Main difference between sections basically explained as their rigidity
Figure 6. Pile Information
modulus are different from each other related with their locations in the structure. Fig.7.
shows joining locations of elevation wall and foundation is in different color, this is because
section properties at that location is different then the other parts of the elevation wall and the
foundation .The idea behind that section difference is that since these locations is near to the
joining point of elevation wall and foundation they represented in software as rigid as possible
so these rigid locations named as ELEVASYON RIJ. and TEMEL RIJ. in the software with
higher rigidity modulus then other parts .
For the assembling process as it mentioned before a 0.5-0.5 m shell element was created at the
beginning, after that for the example in the Fig.7. Auto-CAD drawings for examined and all
the dimensions of the abutment was determined. Then the square shell element that was
created before copied by using offset tool in the software. For instance figure 5 shows the
height of the elevation wall of the structure in Figure 7 and it is around 11 m so if you check
the Fig.7.there are 22 square shell elements along the longitudinal direction. If the dimensions
couldn’t divide by the 0.5 properly we can obtain our structural element by changing the
coordinates of the last shell element. In order to do that operation navigation tool that in the
lower right corner in the software can be used and that tool can be seen in the Figure 8.By
using the coordinates that are provided by navigation tool can be used as guide to complete
correct structure. By using that approach abutment structures was created in the software.
By using shell element abutments with mat foundations can easily be created in the software
but abutments with pile foundations and mixed foundations for the pile part at the foundation
a different approach is used. After pile length was determined from the Auto-CAD file by
using frame tool in the SAP2000 software a 1m long part of the pile was created. After that
using same offsetting tool whole pile foundations is created. Another important point while
creating the piles is that the locations of the piles also be checked from the Auto CAD file and
assemble the correct positions on the abutment structure. In Figure 8 an abutment structure
with pile foundation is shown.
Figure 8. An abutment structure with pile foundation
For the last step of modeling stage, springs are placed beneath the mat foundation and around
the piles if pile foundation exist in the structure. Main purpose of placing this springs is to
simulate effect of soil beneath the foundation or round the piles. In order to do that in a proper
way springs are placed in uniformly manner and this springs show reactions in all 3
dimensions (x-y-z). Reactions that springs are show directly related with the spring constant
that they possess. After springs are placed spring constants were entered to the system and
these constants were increased in every 10-20 m depending on the soil condition and
geotechnical investigation. The determination of spring constants as the engineers in the
company said related with the soil condition and results came from soil investigation test like
CPT (Cone Penetration Test) or SPT (Standard Penetration Test). After that point the
abutment model that worked on so far is ready for the structural analysis stage.
3.3. Structural Analysis :
In order to do the structural analysis first step that needs to be done is the determination of the
loads that acting on the abutment structure. This loads are classified as Dead Load (WDL),
Live Load (WL), Wind Load, Earthquake load, Breaking Load and Lateral Earth
Pressure .This loads were calculated according to various specifications listed below.
Live Load – YKİTŞ(1.3.3)- Turkish General Directorate of Highways Bridge
Specifications
Breaking Load - YKİTŞ(1.3.17) - Turkish General Directorate of Highways
Bridge Specifications
Wind Load - YKİTŞ(1.3.14) - Turkish General Directorate of Highways
Bridge Specifications
Earthquake Load – AASHTO SSHB 1992
Lateral Earth Pressure – YKİTŞ(1.3.22)- Turkish General Directorate of
Highways Bridge Specifications
This load calculations were based on the specifications above and at the company they use
some Excel Macro’s to calculate those loads easily but the idea behind those Excel Macro’s
are used same basis that mentioned in the specifications. In a more detailed manner Dead
Load calculation done according to steps below.
When Dead Load were calculated we need to calculate the forces that are permanently acting
on the structure for a bridge structure these permanent forces acting on abutment structures
can be listed as :
Weight of the Pre-stressed beams
Weight of the bridge floor (Both concrete and asphalt)
Weight of the curb
Weight of the bridge railings
All of these forces above are related with the dimensions of the bridge structure. For the
bridge floor calculation the span length of the bridge, slab and asphalt thicknesses and some
unit weight values needs to be known.
A
After that information was determined from Auto-CAD for all parameter above forces were
calculated in unit weight fashion with a unit of KN/m. For the next step all that unit weights
were summed and multiplied with the span length and Dead Load (WDL) for the bridge
structure were calculated .Since a bridge span stay on top of two abutment structures by
dividing final number by 2 final Dead Load value per an abutment was calculated.
Figure 9. Dimension and unit weight informationFigure 9.Dimension and unit weight information
Figure 10. Dead load Calculations
For the other load types this calculations were done according to specifications that were used
for that specific load type. As mentioned before while these calculations were done Microsoft
Excel were used and only thing that needs to be done was to enter dimension values to excel
sheet. Another important point for load determination process was determining the direction
of those forces. All of these forces were calculated in order to conduct a structural analysis in
the SAP2000 environment. While these forces were entered to the system another important
point is direction of these forces. In the SAP2000 environment you need both direction and
the magnitude of these forces to get a good result from the structural analysis.
In the process of entering forces in to the system there are two different approaches for
different kind of force types. Depending on the force type there are two types of forces; joint
loads and area loads while using the system , two different approaches using for joint loads
and area loads. For joint loads Dead Load, Live Load , Wind Load , Breaking Load and for
area loads Earth Pressure and Earthquake Loads can be listed .
For the joint load entering process there are some important points needs to be considered. At
first these dead loads due to weight of pre-stressed beams, bridge floor and all the other
elements above the abutment structure. Since pre-stressed beams are in direct contact with
the abutment structures, dead loads will transfer to abutment structure through the locations
that pre-stressed beams located as a result of that joint force locations that dead loads placed
in the SAP2000 environment can be taken as locations of pre-stressed beams. At the end
locations and numbers of joint loads were the same with the locations and number of pre-
stressed beams. While joint forces were entered to the system number of beams need to be
determined and same amount of joint force needs to be define on the abutment structure.
These Joint forces need to be placed as much homogenous as possible.
Joint loads were placed between top finishing point of ELEVASYON and start of point of
KALKAN layers that are modeled before. These points are locations of elastomers.
Elastomers are a load transfer mechanism that placed top of ELEVASYON layer and transfer
Dead Load to abutment structure. From the Figure below doted points indicate the points
where Dead Loads were applied in the SAP2000 environment. Also by investigating figure
that can be seen there are 16 pre-stressed concrete beams were used in the structure.
Figure 11. Force Assigning processFigure 11. Force Assigning process
Figure 12. Dead Load locations
By using Assign tool in the SAP2000 environment that can be seen from the Fig.11. we can
assign joint forces to the system and as mentioned before location of the forces are important.
After doing these two steps magnitude and the direction of the forces need to be defined to the
system. While directions of these forces were defined global coordinate system were used in
the software. At this step when magnitudes were entering to the system a load pattern needs to
be selected, by doing that you can easily check and control the forces for the different actions.
These load patterns were defined on the system before and before entering a load correct load
pattern need to be selected and magnitude and direction information were entered to the
system. Another important point is that while different loads were added to the same point for
example: Dead Loads and Live Loads, since the loads applied into the same location from the
panel at the Fig.13. load pattern name was changed to the related load type and also by
enabling to replace existing loads by options segment in the same panel each load was
assigned to its own load pattern.
Area loads were entered in to the software by using a different approach. As it mentioned
before by using “Assign” toolbar area loads were selected. Area loads can be defined as the
loads acting on the areas like earthquake loading and lateral earth pressure .As mentioned in
the joint loads in the case of area loads first thing that needs to be done is selection of the
areas that loads were applied . After areas were selected like the case in the joint loads from
the panel corresponding load type were selected and data were entered into the software .Also
Fig.11. shows the initial parts of the area load assigning process.
Figure 13. Joint Load assigning
From the Fig.14. that can be seen while area loads were entered to the system there is no
magnitude or direction component need to be added to the system .Reason behind is that,
since the forces which were defined as area loads, are the loads that couldn’t be defined using
a direction and a magnitude value, rather than that these forces were entered to the system
using different approaches. For example; when lateral earth pressure was entered to the
system from the panel correct load pattern was selected and by joint pattern option enabled
then by the boxes below again corresponding load type was selected and as the multiplier “-
1” was entered. In order to do all calculations correctly an important trick that need to be done
is, since we are working on an abutment structure it has a certain height. As mentioned before
after abutment structure done on the site “U” shaped part will be filled with soil that’s why
effect of the lateral earth pressure is considered. Because earth pressure is increases from top
to bottom of the structure we type “-1”. Another point is that when lateral pressure was
assigned to the structure move the top point in the structure to ground level which is “0” m
then assign the lateral earth pressure. This moving process is mainly related with how the
Figure 14. Area load assigning
lateral earth pressure was defined in the software. Like lateral earth pressure , earthquake
loading also defined as areal loading and the only difference between those two loading , in
earthquake loading as multiplier “1” was typed in to the system again due to the definition of
the earthquake loading in the software.
In the software any kind of loading can be defined and modified .According to Fig.15. there
are various of load patterns defined in the structure and these can be used without any
modification in the time of need.
After modelling and load assigning parts were finished now the virtual copy of the abutment
structure was ready for the structural analysıs part by using analyzing tools available in the
software. After some time from the start of analysıs result were ready for further inspection.
Immediately after the software finishes structural analysis in the screen the structure that
modeled in the previous stage was available and if any adverse condition or structural defect
occurred after the structural analysis result these are shown in the modelled structure. Also in
the screen if you move your mouse to the joint points in the structure displacement and
rotation values were shown in the screen and that can be seen from figure below. From the
Fig.16. that can be seen there are 3 displacement and 3 rotation values these 3 parameters
Figure 15. Load patterns defined on SAP2000
were with respect to the global x , global y and global z axis. Furthermore there are some
deformations in the abutment structure can be seen in the corner of the structure.
For further inspections moments, normal forces and shear forces acting on the structure can be
listed or can be shown on the structure as heat map formation. This inspections can be done
for whole structure or can be done by separately for the structural elements in the abutment
structure. Mat foundation, structural walls and pile foundations can be inspect separately from
each other. This structural analysis were done using Load and Resistance Factor Design
(LRFD) and each combination defined in the system after loads were entered the system
software done the structural analysis according to those load combinations and shown in the
figures below . Fig.17. shows the different moment and shear forces acting on the mat
foundation by the effect of different load combinations. As can be seen in the Fig.17. all 4
combinations results different effects on the structure to be o the safe side reinforcement
design were done taking the most critical values from the all possible combinations.
Figure 16. Displacement and rotation values
Furthermore from Fig.18. same things can be seen and the same procedure was repeated for
the structural walls that can be seen in the Fig.18 .
Figure 17. Shear force and moment heat maps for foundation
Figures above shows the moments and shear forces acting on a mat foundation and structural
walls of an abutment structure. These two components were defined as shells in SAP2000
environment .As mentioned before pile foundations were represented by frame elements and
those moments and forces can also be shown on the pile as well as on Microsoft excel. From
the figure below forces and moments acting on the piles and girder flange can be seen. While
abutment structure was constructed in the need of pile foundation; after piles were constructed
all piles were connected to each other with the girder flange so in the analysis they are shown
together.
Figure 18. Shear force and moment heat maps for structural wall
Figure 19. Moment diagram for piles and girder flange
Figure 20. Shear force diagram for piles and girder flange
Other than showing these analysis result on the structure as heat map we can export analysis
result to Microsoft Excel and see them in a more organized fashion. In order to do that ,after
structural analysis were done analysıs result could be shown in a tabulated format by using
display tool and clicking show tables option from that point results were tabulated from the
file options this tables can be exported to the Microsoft Excel . By using the features of the
Microsoft Excel this result can be re-arranged in to desired format. From the figure it is easier
to see the load combinations and corresponding moment, normal and shear forces.
Figure 21. Analysis results on MS. Excel sheet
3.4. Final Design :
After structural analysis part was finished, moment, normal force and shear force values were
available to be used in further in the final design part. For this stage the main purpose of the
calculations is to obtain amount of the reinforcement steel that used in the structure. For that
calculations in the company they use some Microsoft Excel macros that were prepared before
by using AASHTO Bridge Design Specifications. Idea behind those Excel sheets are same
with the knowledge that are learnt from the Reinforced Concrete lesson.
From the structural analysis results moments are available , concrete grade and steel grade
were taken from data available in the excel sheet .After that moment value were entered to the
system and also section dimensions were entered to the system from the Fig.22. the
parameters that can be changed by the users were indicated by red color. Moment value,
dimensions and steel diameter and amount are the parameters that can be changed by users.
Figure 22. Reinforcement calculations 1
From Fig.23. ρ b represent the balanced steel ration and its basically As/(bw*d) after this
calculations were done ρ max value were calculated, from the reinforced concrete course ρ max=
0.85*ρ b beyond that limit our design started to lose its ductility beyond this limit is not
allowed so at the and this number is a check for our design .
From the Fig.23. when ρ max was calculated they multiply ρ b with 0.75 that would be done in
order to be on the safe side. By doing so at the end more conservative ρ max value was
obtained.
For the last part moment capacity of our structure and the moment that our structure was
exposed were compared and by changing the amount of steel the moment capacity that can be
withstand to applied moments. Also as mentioned in the Fig.23. resisting moment was
calculated by Mn= A steel * f y * (d-(k1*c)/2). From the figure moment carrying capacity
calculated as 1622.96 KN.m and this is bigger than applied moment. For the last check ρ max
and calculated ρ values were compared and since ρ is smaller than ρ max this design can be
acceptable.
Figure 23. Reinforcement calculations 2
From the Fig.24. that can be seen shear design and design against cracking was done
accordingly. In order to do that shear force was taken from structural analysis results and at
the end shear capacity and shear force that been applied to the structure was compared and
design was acceptable .
4. CONCLUSION :
This report contains four main parts; introduction, company history, structural analysis and
conclusion furthermore detailed information about modeling and structural analysis stage was
given. During my internship, project related with bridge design and its structural analysis was
examined and basics of SAP2000 structural analysis software was tried to be learn and
understood. Also I have gained experience on running of a design office. This is important
because I want to connect my theoretical knowledge with practical one as well. Moreover, at
the end of the my summer practice I was able to increase both communication and group
working skills .Furthermore I was able to learn the importance of the design part of the project
and by getting involved in the working of an office I tried to understood the paperwork that
done with ministries as well. Also sawing the working conditions on a project office help to
decide what I was done after graduation.
Figure 24. Reinforcement calculations 3
REFERENCES
AASHTO LRFD 2012 Bridge Design Specifications, AASHTO Publications Staff (2012), 6th edition.
Ersoy, U., Özcebe, G., and Tankut, T. (2003). Reinforced Concrete. Metu Press.
Güngor G., Aşık I. , Fekardan H. , Demir E. (2013), Turkish General Directorate of Highways Bridge
Specifications, Revised version.
INPRO engineering (2014).” Institutional and Projects.” < http://www.inprotr.com> (Oct. 16, 2015).
INPRO Engineering and Consultancy Company Manavgat – Akseki road Üzümdere Bridge Structural
Analysis Report (2014)