Comparison of various procedures for progressive collapse analysis of cable-stayed bridges

Alternate path(AP) method is the most widely used method for the progressive collapse analysis,and its application in frame structures has been well proved.However,the application of AP method for other structures,especially for cable-stayed structures,should be further developed.The four analytical procedures,i.e.,linear static,nonlinear static,linear dynamic,and nonlinear dynamic were firstly improved by taking into account the initial state.Then a cable-stayed structure was studied using the four improved methods.Furthermore,the losses of both one cable and two cables were discussed.The results show that for static and dynamic analyses of the cable-stayed bridges,there is large difference between the results obtained from simulations starting with either a deformed or a nondeformed configuration at the time of cable loss.The static results are conservative in the vicinity of the ruptured cable,but the dynamic effect of the cable loss in the area farther away from the loss-cable cannot be considered.Moreover,the dynamic amplification factor of 2.0 is found to be a good estimate for static analysis procedures,since linear static and linear dynamic procedures yield approximately the same maximum vertical deflection.The results of the comprehensive evaluation of the cable failure show that the tread of the progressive failure of the cable-stayed bridges decreases when the location of the failed cables is closer to the pylon.

基于无损检测与木材力学性能相关性的既有木构件剩余抗弯承载力研究（英文）

目的:利用无损检测的方法,定量评估经腐朽和虫蛀后的既有木构件的剩余抗弯承载力。方法:1.通过对木材小试件进行阻抗仪检测试验和材性试验,建立木材阻力值与抗压/抗拉强度之间的线性回归方程;2.对大段木梁试件进行阻抗仪检测试验,基于木材阻力值与抗压/抗拉强度之间的关系,计算得到大段木梁各部分的强度值;3.在Abaqus中对既有木梁的初始缺陷进行模拟并将木梁的计算强度值赋予木梁的各个部分,综合分析木梁的剩余抗弯承载力。结论:1.木材小试件的阻力值与抗压/抗拉强度值之间呈现出显著的相关性,各测点处的木材强度值可通过阻力值计算得到;2.虫蛀、木节和裂缝等初始缺陷对试件的破坏形式和极限荷载影响显著;3.非线性仿真分析所得的结果与试验结果基本吻合。