A novel approach to the dynamic response analysis of Euler-Bernoulli beams resting on a Winkler soil model and subjected to impact loads

This work presents a novel approach to the dynamic response analysis of a Euler-Bernoulli beam resting on a Winkler soil model and subjected to an impact loading.The approach considers that damping has much less importance in controlling the maximum response to impulsive loadings because the maximum response is reached in a very short time,before the damping forces can dissipate a significant portion of the energy input into the system.The development of two sine series solutions,relating to different types of impulsive loadings,one involving a single concentrated force and the other a distributed line load,are presented.This study revealed that when a simply supported Euler-Bernoulli beam,resting on a Winkler soil model,is subject to an impact load,the resulting vertical displacements,bending moments and shear forces produced along the span of the beam are considerably affected.In particular,the quantification of this effect is best observed,relative to the corresponding static solution,via an amplification factor.The computed impact amplification factors,for the sub-grade moduli used in this study,were in magnitude greater than 2,thus confirming the multiple-degree-of-freedom nature of the problem.

光面钢筋混凝土柱的地震响应 第一部分:单调试验

最新国内和国际的抗震规范对既有建筑和新设计结构抗震评估之间的差异进行了论述。发布了材料结构特征的详细指南,以及完成可靠性分析的特有程序。光面钢筋混凝土结构的抗震性能模型具有重要作用,需要进一步完善。对钢筋混凝土柱的试验结果进行了报道,这些钢筋混凝土柱按照老规范设计,可追溯到20世纪40-70年代。研究聚焦在单调荷载下构件的转动能力以及对两个文献中拓展研究报告的第一部分进行描述,两个文献均对单调和循环问题进行研究。

光面钢筋混凝土柱的地震响应 第二部分:循环试验

既有建筑的抗震性能评估中,钢筋混凝土构件的转动能力评估是一个关键问题。在现代安全评估体系中,必须进行抗震需求和抗震能力的比较。然而,可采用的性能模型只能反映允许钢筋变形的新结构的试验结果,其变形和强度机制并非必须反映旧构件的响应。众所周知,按照旧规范设计的钢筋混凝土构件,通过不同的结构细节、不完善的约束、光面钢筋和混凝土之间弱的粘结来描绘其特性。与新结构相比,出现了不同的屈服后机制。根据意大利1940-1970年的指南设计了光面钢筋混凝土柱,并报道其第二阶段试验结果。在循环荷载下,对构件的研究结果清楚地显示了在转动能力发展过程中弱粘结的作用。相关的研究涉及柱的单调响应和由欧洲规范8规定的经验公式所确定的弦的转动。