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101.
软土地基工后沉降预测模型的研究 总被引:3,自引:1,他引:2
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Building structures damaged by a seismic event may be exposed to the risk of aftershocks or another event within a certain period. In this paper, the seismic assessment of damaged piloti‐type RC buildings was carried out to evaluate probabilistic retrofitting effects under successive earthquakes. First, a framework to evaluate the effectiveness of retrofitting was proposed, and then the proposed methodology was demonstrated with a structure retrofitted with buckling‐restrained braces (BRBs). For consideration of realistic successive earthquakes, past records measured at the same station were combined. Within the framework, a series of nonlinear time history analyses were performed for an as‐is model subjected to single earthquake, a damaged model subjected to successive earthquakes, and a damaged model retrofitted with BRBs subjected to successive earthquakes. In addition, fragility analysis was systematically applied in the framework for evaluation of effectiveness of the retrofitting strategy. The proposed framework was capable of quantifying the influence of successive earthquakes and evaluating the effectiveness of BRB retrofitting by considering the severity of the first earthquake damage and the hysteresis behavior of the retrofit element. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Gaps between beam‐to‐column interfaces in a post‐tensioned (PT) self‐centering frame with more than one column are constrained by columns, which causes beam compression force different from the applied PT force. This study proposes an analytical method for evaluating column bending stiffness and beam compression force by modeling column deformation according to gap‐openings at all stories. The predicted compression forces in the beams are validated by a cyclic analysis of a three‐story PT frame and by cyclic tests of a full‐scale, two‐bay by first‐story PT frame, which represents a substructure of the three‐story PT frame. The proposed method shows that compared with the strand tensile force, the beam compression force is increased at the 1st story but is decreased at the 2nd and 3rd stories due to column deformation compatibility. The PT frame tests show that the proposed method reasonably predicts beam compression force and strand force and that the beam compression force is 2 and 60% larger than the strand force with respect to a minor restraint and a pin‐supported boundary condition, respectively, at the tops of the columns. Therefore, the earlier method using a pin‐supported boundary condition at upper story columns represents an upper bound of the effect and is shown to be overly conservative for cases where a structure responds primarily in its first mode. The proposed method allows for more accurate prediction of the column restraint effects for structures that respond in a pre‐determined mode shape which is more typical of low and mid‐rise structures. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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以中铁西安中心超高层建筑为工程背景,采用后压浆钻孔灌注桩技术对该工程进行地基处理。工程中测试钻孔灌注桩压浆前、后单桩竖向抗压静载试验及桩身内力。采用建筑桩基技术规范、侧阻、端阻分项增强系数法、基于极限承载力增强系数法和只考虑桩端改善承载力5种方法进行了后压浆桩的桩基极限承载力计算。结果表明,后压浆后桩基极限承载力提高了24%,侧阻、端阻分项增强系数法和基于极限承载力增强系数法与现场实测最接近;建筑桩基技术规范与只考虑桩端承载力改善与现场实测结果相差较大,其计算值偏于安全保守。 相似文献
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川西北平武地区南一里花岗岩体地球化学特征及其构造环境 总被引:2,自引:0,他引:2
对出露于碧口地块西南部的南一里岩体进行了系统的地球化学研究,重点讨论了南一里岩体的岩石成因、成岩物质来源及其构造环境。该岩体的SiO2和Al2O3的含量均很高,SiO2含量变化为71.29%~73.05%,A/CNK在1.07~1.11之间;FeO/(FeO+MgO)比值较低,为硅和铝过饱和类型,属典型的强过铝质花岗岩。稀土元素总量(∑REE)为56.80×10-6~89.12×10-6,稀土元素配分曲线呈右倾型,具有弱的负铕异常。Ta、Nb、P、Ti等高场强元素具有明显的负异常,而Rb和Sr等大离子亲石元素具有明显的正异常。岩浆源区可能是以杂砂岩成分为主的沉积岩部分熔融形成的花岗质岩浆上升侵位形成的,是一种典型的壳源成因类型。南一里岩体具有后碰撞岩浆活动的特征,是印支期华北地块和扬子地块碰撞导致地壳加厚环境下下地壳部分熔融的产物,形成于同碰撞(挤压环境)向碰撞后(伸展环境)转化阶段,为后造山花岗岩类。 相似文献
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