开展钢筋混凝土薄壁空心桥墩抗震问题的研究,对保证大型桥梁结构抗震安全具有重要意义。首先设计2个矩形薄壁空心墩试件,分别进行定轴力和变轴力下的拟静力试验,发现试件前期破坏以弯曲和剪切开裂为主,其后发生混凝土压碎脱落,纵筋屈曲...开展钢筋混凝土薄壁空心桥墩抗震问题的研究,对保证大型桥梁结构抗震安全具有重要意义。首先设计2个矩形薄壁空心墩试件,分别进行定轴力和变轴力下的拟静力试验,发现试件前期破坏以弯曲和剪切开裂为主,其后发生混凝土压碎脱落,纵筋屈曲等现象;最终试件薄壁发生突然的失稳破坏,引起桥墩倒塌。基于薄壁空心墩试验结果对国内外主要桥梁抗震设计规范和学者们提出的抗剪分析模型进行对比分析,认为我国《公路桥梁抗震设计细则》和欧洲Eurocode 8规范较为准确的计算了各试件抗剪强度或得到偏于保守的结果,可用于薄壁空心墩的抗剪设计;UCSD模型和Aschhiem模型高估了试件的抗剪能力,不适合于对薄壁空心桥墩的抗剪强度分析,而提出的改进的UCSD模型很好的预测了薄壁空心墩的抗剪强度。修正的压力场理论(Modified Compression Field Theory,MCFT)计算的薄壁空心墩抗剪强度最为准确。展开更多
An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural-shear failure mode. Six circular pier specimens were f...An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural-shear failure mode. Six circular pier specimens were first tested to severe damage in flexural-shear mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers （CFRP）. After about four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure mechanism of the piers shifted from flexural-shear failure to ductile flexural failure. Finally, a simple design model based on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.5 times more FRP sheets is provided.展开更多
Capacity of components subjected to earthquake actions is still a widely interesting research topic. Hence, developing precise tools for predicting drift capacities of reinforced concrete (RC) columns is of great inte...Capacity of components subjected to earthquake actions is still a widely interesting research topic. Hence, developing precise tools for predicting drift capacities of reinforced concrete (RC) columns is of great interest. RC columns are not only frequently constructed, but also their composite behavior makes the capacity prediction a task faced with many uncertainties. In the current article, novel empirical approaches are presented for predicting flexural, shear and axial failure modes in RC columns. To this aim, an extensive experimental database was created by collecting outcomes of previously conducted experimental tests since 1964, which are available in the literature. It serves as the basis for deriving the equations for predicting the drift capacity of RC columns by different regression analyses (both linear with different orders and nonlinear). Furthermore, fragility curves are determined for comparing the obtained results with the experimental results and with previously proposed models, like the ones of ASCE/SEI41-13. It is demonstrated that the proposed equations predict drift capacities, which are in better agreement with experimental results than those computed by previously published models. In addition, the reliability of the proposed equations is higher from a probabilistic point of view.展开更多
文摘开展钢筋混凝土薄壁空心桥墩抗震问题的研究,对保证大型桥梁结构抗震安全具有重要意义。首先设计2个矩形薄壁空心墩试件,分别进行定轴力和变轴力下的拟静力试验,发现试件前期破坏以弯曲和剪切开裂为主,其后发生混凝土压碎脱落,纵筋屈曲等现象;最终试件薄壁发生突然的失稳破坏,引起桥墩倒塌。基于薄壁空心墩试验结果对国内外主要桥梁抗震设计规范和学者们提出的抗剪分析模型进行对比分析,认为我国《公路桥梁抗震设计细则》和欧洲Eurocode 8规范较为准确的计算了各试件抗剪强度或得到偏于保守的结果,可用于薄壁空心墩的抗剪设计;UCSD模型和Aschhiem模型高估了试件的抗剪能力,不适合于对薄壁空心桥墩的抗剪强度分析,而提出的改进的UCSD模型很好的预测了薄壁空心墩的抗剪强度。修正的压力场理论(Modified Compression Field Theory,MCFT)计算的薄壁空心墩抗剪强度最为准确。
基金National Natural Science Foundation of China Under Grant No.51008041 and 50978042the National Special Foundation of Earthquake Science of China Under Grant No.200808021the Fundamental Research Funds for the Central Universities Under Grant No.2011JC011
文摘An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural-shear failure mode. Six circular pier specimens were first tested to severe damage in flexural-shear mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers （CFRP）. After about four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure mechanism of the piers shifted from flexural-shear failure to ductile flexural failure. Finally, a simple design model based on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.5 times more FRP sheets is provided.
文摘Capacity of components subjected to earthquake actions is still a widely interesting research topic. Hence, developing precise tools for predicting drift capacities of reinforced concrete (RC) columns is of great interest. RC columns are not only frequently constructed, but also their composite behavior makes the capacity prediction a task faced with many uncertainties. In the current article, novel empirical approaches are presented for predicting flexural, shear and axial failure modes in RC columns. To this aim, an extensive experimental database was created by collecting outcomes of previously conducted experimental tests since 1964, which are available in the literature. It serves as the basis for deriving the equations for predicting the drift capacity of RC columns by different regression analyses (both linear with different orders and nonlinear). Furthermore, fragility curves are determined for comparing the obtained results with the experimental results and with previously proposed models, like the ones of ASCE/SEI41-13. It is demonstrated that the proposed equations predict drift capacities, which are in better agreement with experimental results than those computed by previously published models. In addition, the reliability of the proposed equations is higher from a probabilistic point of view.
