Genetic-programming-based Modeling of RC Beam Torsional Strength

Abdulkadir Cevik,Musa Hakan Arslan,Mehmet Alpaslan Koroglu 대한토목학회 2010 KSCE Journal of Civil Engineering Vol.14 No.3

This study investigates the use of Genetic Programming (GP) to model Reinforced Concrete (RC) beam torsional strength. Experimental data of 76 rectangular RC beams from an existing database were used to develop the GP model. The following input parameters, which affect torsional strength, were selected: beam cross-sectional area, closed stirrup dimensions, stirrup spacing,closed stirrup cross-sectional area of one leg, stirrup and longitudinal reinforcement yield strength, stirrup steel ratio, longitudinal reinforcement steel ratio and concrete compressive strength. Moreover, a short review of well-known building codes in relation to the design of RC beams under pure torsion is presented. The accuracy of the codes in predicting the RC beam torsional strength was also compared with the proposed GP model using the same test data. The study concludes that the proposed GP model predicts RC beam torsional strength more accurately than building codes

Numerical evaluation of effects of shear span, stirrup spacing and angle of stirrup on reinforced concrete beam behaviour

Yasin Onuralp Özkılıç,Ceyhun Aksoylu,Musa Hakan Arslan 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.3

Shear and bending strength of reinforced concrete beams depend on many parameters. It is extremely important to take the necessary precautions in terms of shear in order for the beams to reach their bending capacity. For this reason, it is necessary to determine the effective parameters especially on shear capacity in beams. However, the actual capacity calculation is quite difficult according to regulations that are very conservative in terms of design. Therefore, many experimental studies have been conducted on the shear capacity of the beams. However, this situation is not meaningful in terms of both time and cost, since many experiments will be required to interpret the beam shear behavior, which depends on many parameters. For this reason, the use of advanced software whose verification is performed according to experimental data has become widespread. In this study, a numerical study was carried out on 36 different beam models using the ABAQUS finite element program to examine the effect of the shear span/effective depth (av/d) ratio, stirrup spacing (sw) and the angle of stirrup (α). The results showed that as the av/d increase, the behavior of a shear deficient beam tends to typical bending behavior. Although the effect of stirrup angle on shear capacity is quite high, stirrup angles of 30° and 60° give very similar results. The effect of stirrup spacing is quite limited at relatively high av/d. Stirrups with 90° do not contribute to ductility in beams with high av/d.

Optimum amount of CFRP for strengthening shear deficient reinforced concrete beams

Lokman Gemi,Mohammed Alsdudi,Ceyhun Aksoylu,Şakir Yazman,Yasin Onuralp Özkılıç,Musa Hakan Arslan 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.43 No.6

The behavior of shear deficient under-balanced reinforced concrete beams with rectangular cross-sections, which were externally strengthened with CFRP composite along shear spans, was experimentally investigated under vertical load. One of the specimens represents a reference beam without CFRP strengthening and the other specimens have different width/strip spacing ratios (wf/sf). The optimum strip in terms of wf/sf, which will bring the beam behavior to the ideal level in terms of strength and ductility, was determined according to the regulations. When the wf/sf ratio exceeds 0.55, the behavior of the beam shifted from shear failure to bending failure. However, it has been observed that the wf/sf ratio should be increased up to 0.82 in order for the beam to reach sufficient shear reserve value according to the codes. It is also observed that the direction and weight of the CFRP composite are one of the most critical factors and 240 gr/m2 CFRP strips experienced sudden ruptures in the shear span after the cracking of the concrete. It is considered as a deficiency that the empirical shear capacity formulas given for the beams reinforced with CFRP in the regulations do not take into account both direction and weight of CFRP composites.

Numerical and analytical investigation of parameters influencing the behavior of shear beams strengthened by CFRP wrapping

Ceyhun Aksoylu,Yasin Onuralp Özkılıç,Şakir Yazman,Mohammed Alsdudi,Lokman Gemi,Musa Hakan Arslan 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.2

In this study, a parametric study was performed considering material properties of concrete, material properties of steel, the number of longitudinal reinforcement (reinforcement ratio), CFRP ply orientations, a number of layers as variables by using ABAQUS. Firstly, the parameters used in the Hashin failure criteria were verified using four coupon tests of CFRP. Secondly, the numerical models of the beams strengthened by CFRP were verified using five experimental data. Finally, eighty numerical models and eighty analytic calculations were developed to investigate the effects of the aforementioned variables. The results revealed that in the case of using fibrous polymer to prevent shear failure, the variables related to reinforced concrete significantly affected the behavior of specimens, whereas the variables related to CFRP composite have a slight effect on the behavior of the specimens. As a result of numerical analysis, while the increase in the longitudinal tensile and compression reinforcement, load bearing capacity increases between 23.6%-70.7% and 5.6%-12.2%, respectively. Increase in compressive strength (29 MPa to 35 MPa) leads to a slight increase in the load-carrying capacity of the specimens between 4.6% and 7.2%. However, the decrease in the compressive strength (29 MPa to 20 MPa) significantly affected (between 6.4% and 8.1% decrease observed) the behavior of the specimens. As the yield strength increases or decreases, the capacity of specimens increase approximately 27.1% or decrease 12.1%. The effects of CFRP ply orientation results have been obtained as a negligible well approximately 3.7% difference. An increasing number of CFRP layers leads to almost no effect (approximately 2.8%) on the behavior of the specimen. Finally, according to the numerical analysis, the ductility values obtained between 4.0 and 6.9 indicate that the beams have sufficient ductility capacity.

Use of waste steel fibers from CNC scraps in shear-deficient reinforced concrete beams

İlker Kalkan,Yasin Onuralp Özkılıç,Ceyhun Aksoylu,Md Azree Othuman Mydin,Carlos Humberto Martins,Ibrahim Y. Hakeem,Ercan Işık,Musa Hakan Arslan 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.49 No.2

The present paper summarizes the results of an experimental program on the influence of using waste lathe scraps in the concrete mixture on the shear behavior of RC beams with different amounts of shear reinforcement. Three different volumetric ratios (1, 2 and %3) for the scraps and three different stirrup spacings (160, 200 and 270 mm) were adopted in the tests. The shear span-to-depth ratios of the beams were 2.67 and the stirrup spacing exceeded the maximum spacing limit in the building codes to unfold the contribution of lathe scraps to the shear resistances of shear-deficient beams, subject to sheardominated failure (shear-tension). The experiments depicted that the lathe scraps have a pronounced contribution to the shear strength and load-deflection behavior of RC beams with widely-spaced stirrups. Namely, with the addition of 1%, 2% and 3% waste lathe scraps, the load-bearing capacity escalated by 9.1%, 21.8% and 32.8%, respectively, compared to the reference beam. On the other hand, the contribution of the lathe scraps to the load capacity decreases with decreasing stirrup spacing, since the closely-spaced stirrups bear the shear stresses and render the contribution of the scraps to shear resistance insignificant. The load capacity, deformation ductility index (DDI) and modulus of toughness (MOT) values of the beams were shown to increase with the volumetric fraction of scraps if the stirrups are spaced at about two times the beam depth. For the specimens with a stirrup spacing of about the beam depth, the scraps were found to have no considerable contribution to the load capacity and the deformation capacity beyond the ultimate load. In other words, for lathe scrap contents of 1-3%, the DDI values increased by 5- 23% and the MOT values by 63.5-165% with respect to the reference beam with a stirrup spacing of 270 mm. The influence of the lathe scraps to the DDI and MOT values were rather limited and even sometimes negative for the stirrup spacing values of 160 and 200 mm.