THE HIGH PERFORMANCE CONCRETE

Abstract of The Phd Thesis

1. Introduction According with the FIB definition, the high performance concrete have the

compression resistance on cilinders between 60MPa and 130MPa and the water/cement ratio smaller than 0.40.

The Phd thesis contain an extensive presentation of the high performance concrete characteristics in the first part and, in the second one, the results of the numerical experiments on four tall frame structures realised from concrete of C16/20, C50/60, C90/105 and C100/115 classes and reinforcement S500H. The designing used code was Eurocode2. Following the european design rules, the structure must assure:

adequated performances on all possible actions, durability, the damages values under exceptional actions must be controlled.

To optimize the building’s elements design process using the new materials and using the european design rules, we must have the proper design algorithms to control all the parameters involved. Hereby, in this Phd-thesis it is presented the design algorithms for the high performance concrete beams and columns reinforced with S500H steel, based on the Eurocode 2 relations, generalised by the author for the high performance concrete. Using this relations to the numerical experiments it was obtained the results presented below. The design characteristics for concrete and reinforcements are gived in the tables

1 and 2. Tabel 1. The concrete design characteristics.

C12 /15

C16/20

C20/25

C25/30

C30/37

C35/45

C40/50

C45/55

C50/60

C55/67

C60/75

C70/85

C80/95

C90/105

C100 /115

fck [N/mm2] 12 16 20 25 30 35 40 45 50 55 60 70 80 90 100 fctm [N/mm2] 1,6 1,9 2,2 2,6 2,9 3,2 3,5 3,8 4,1 4,2 4,4 4,6 4,8 5,0 5,2 fctk0,05 fctk0,95

[N /m2] 1,1 2,1

1,3 2,5

1,5 2,9

1,8 3,3

2,0 3,8

2,2 4,2

2,5 4,6

2,7 4,9

2,9 5,3

3,0 5,5

3,1 5,7

3,2 6,0

3,4 6,3

3,5 6,6

3,7 6.8

Ecm [kN/mm2] 27 29 30 31 33 34 35 36 37 38 39 41 42 44 45

Tabelul 2. The reinforcements design characteristics.

S500H S1 fyk [N/mm2] 500.00 fyd [N/mm2] 434.78 E [kN/mm2] 200.00 γs [daN/m3] 7850.00 εs [‰] 2.20

2. The structures geometry and shape of the studied structures

In figure 1 is represented the basic structural shape in axonometrical

representation, as cross-section and drawing.

3. The cross-section dimensions of the structural elements. After the structural calculus, we obtain the dimensions for the frame elements

(beams and columns). The following concluding observations are obtained: ▪ the cross-sections ratio of the beams for the structures indicate: a

diminution with 8.33% at S2 structure than S1 structure, a diminution with 24.24% at S3 structure than S2 structure and a diminution with 10% at S4 structure than S3 structure,

▪ the corner columns cross-section at P-I-II levels are with 64% smallers at S2 than S1, with 20.98% smallers at S3 than S2 and with 23.43% smaller at S4 than S3,

▪ the corner columns cross-sections at III-IV-V-VI levels are with 65.97% smallers at S2 than S1, they are equals at S2 and S3, and with 26.53% smallers at S4 than S3,

▪ the corner columns cross-sections at VII-VIII-IX-X are with 55.55% smallers at S2 than S1, and equals at S2, S3 and S4,

▪ the marginal columns cross-sections at P-I-II are with 65.39% smallers at S2 than S1, with 19% smallers at S3 than S2 and with 20.98% smallers at S4 than S3,

▪ the marginal columns cross-sections at III-IV-V-VI are with 58.67% smallers at S2 than S1, with 20.98% smallers at S3 than S2 and with 23.43% smallers at S4 than S3,

Fig.1. The structures geometry: a) axonometry, b) cross section,

c) drawing.

a) b)

c)

▪ the marginal columns cross-sections at VII-VIII-IX-X are with 51% smallers at S2 than S1, with 26.43% smallers at S3 than S2 and they are equals at S3 and S4,

▪ the internal columns cross-sections at P-I-II are with 64% smallers at S2 than S1, with 30.55% smallers at S3 than S2 and with 19% smallers at S4 than S3,

▪ the internal columns cross-sections at III-IV-V-VI are with 65.39% smallers at S2 than S1, with 36% smallers at S3 than S2 and with 23.43% smallers at S4 than S3,

▪ the internal columns cross-sections at VII-VIII-IX-X are with 55.55% smallers at S2 than S1, with 43.75% smallers at S3 than S2 and they are equals at S3 and S4.

In general, the columns cross-section reductions for the choosed structures are

gived by the following values: ▪ for corner columns: with 62.98% smallers at S2 than S1, with 8.75%

smallers at S3 than S2 and with 18.23% smallers at S4 than S3, ▪ for marginal columns: with 60.01% smallers at S2 than S1, with 21.58%

smallers at S3 than S2 and with 17.26% smallers at S4 than S3, ▪ for internal columns: with 62.89% smallers at S2 than S1, with 35.66%

smallers at S3 than S2 and with 16.71% smallers at S4 than S3. As a consequence of resistance elements cross-sections reduction, the total

building weights are reduced as well. Thus, the S2 weight is with 13.29% smaller than S1, the one of S3 is 6.45% smaller than S2 and with 2.70% the one of S4 structure than S3. A direct effect of this weights reduction is the seismic forces reduction for the buildings.

4. The total materials quantities used for the resistance structures. Concluding remarqs.

Based on the obtained results the followings concluding remarqs can be maked: ▪ the concrete quantities used indicate a decreasing with 34.35% at S2 than

S1, with 24.07% at S3 than S2 and a decreasing with 12.36% at S4 than S3,

▪ the steel quantities used for the beams longitudinal reinforcement shown a decreasing with 13.07% at S2 than S1, a decreasing with 8.74% at S3 than S2 and an increase with 6.01% at S4 than S3,

▪ the steel quantities used for the columns longitudinal reinforcement shown a decreasing with 6.11% at S2 than S1, a decreasing with 7.32% at S3 than S2 and an increase with 5.93% at S4 than S3,

▪ the steel quantities used for the beams transversal reinforcement shown a decreasing with 2.35% at S2 than S1, a decreasing with 14.26% at S3 than S2 and a decreasing with 5.46% at S4 than S3,

▪ the steel quantities used for the columns transversal reinforcement shown a decreasing with 40.98% at S2 than S1, a decreasing with 12.52% at S3 than S2 and a decreasing with 10.32% at S4 than S3,

▪ generally, the total steel quantities used for the beams and columns reinforcement shown a decreasing with 12.57% S2 than S1, a decreasing with 8.98% at S3 than S2 and an increasing with 3.19% at S4 than S3.

Analysing this final comparative dates we can observe that the S3 and S4 structures are the most atractive by the material economy point of view. This fact, added to the practical space gained by the structural elements dimensions reductions, recommend the high performance concrete to be used to the multistored structures in the Cluj-Napoca area. 5. Graphical representation of the results

Figure 2. Concrete quantities for beams of S1, S2, S3 and S4.

Figure 3. Concrete quantities for columns of S1, S2, S3 and S4.

Figure 4. Total concrete quantities of S1, S2, S3 and S4.

Figure 5. Longitudinal reinforcement for beams. S1, S2, S3 and S4.

Figure 6. Transversal reinforcement for beams. S1, S2, S3 and S4.

Figure 7. Longitudinal reinforcement for columns. S1, S2, S3 and S4.

Figure 7. Transversal reinforcement for columns. S1, S2, S3 and S4.

6. Concluding remarqs. Personal contributions. In the present thesis, the author develope the following personal contribution to the high performance concrete domain:

a large documentation of the known researches for this type of concrete, the high performance concrete behaviour analysis in the ultimate limit state, the relations based on Eurocode 2 are generalised, and the values for the coefficients involved are gived, general calculus relations of the high performance concrete for: simple and double reinforced sections of rectangular and „T” beams at simple bending, bending with axial force, biaxial bending, shear force and bending, torsion, the general algorithms based on Eurocode 2 for the high performance concrete are expressed, it was demonstrated the viability of the high performance concrete (C90/105 and C100/115) with S500H reinforcement utilization for the frame structures of the tall building in Cluj-Napoca, an extensiv graphical representation was made for efforts, concrete and reinforcement quantities used to the studied structures. Also, a large procentual comparison was made for all this values.

The obtained results are partially published in 10 scientific papers as first author

or coauthor.