软土地基上带圈梁构造柱砌体结构的非线性有限元分析

本文对软土地基上带圈梁构造柱的砌墙体进行了非线性有限元全过程分析。根据砌体、混凝土和钢筋各自的本构关系，采用八结点等参元有限元进行求解。在分析过程中，考虑砌体出现的开裂与开裂过程中的应力迁移，讨论了各种工况对墙体的内力分布带来的影响。     

兰聊断裂南段构造样式与最新活动性分析

兰聊断裂南段构造样式复杂,分段活动特征明显。已有学者针对兰聊断裂的研究,主要集中在范县—东明县一带,而兰聊断裂南段的构造样式与最新活动性研究匮乏。为此采用地震反射剖面与钻孔联合剖面探测方法,对兰聊断裂南段进行较系统地分析,认为兰聊断裂南段构造样式为伸展走滑断裂尾端“马尾扇”结构,其最新活动时代为中更新世中晚期,晚更新世以来未活动,中更新世最大滑动速率为0.061 mm/a,据此判断兰聊断裂南段为中更新世断裂。     

再生混凝土砖砌体抗压性能试验研究

再生混凝土砖是利用废弃混凝土作为骨料制作的一种砖,作为再生混凝土砖砌体抗震性能研究的基础,文中进行了18个不同砂浆强度的再生混凝土砖砌体的抗压性能试验。测试分析了各试件的承载力、变形和破坏过程,得到了再生混凝土砖砌体的抗压强度、弹性模量和泊松比。研究表明:再生混凝土砖砌体与普通黏土砖砌体相比,承载力略低,抗压强度退化略快,弹性模量和泊松比接近;随着砌筑砂浆强度的提高,再生混凝土砖砌体的承载力和变形能力提高,弹性模量增大。再生混凝土砖砌体可用于多层砌体房屋结构抗震设计。     

开鲁盆地陆西凹陷下白垩统层序地层学和油气评价

开鲁盆地陆西凹陷是一个典型的中生代单断箕状盆地,充填了厚达3000余米的下白垩统并表现出良好的沉积旋回特征.依据钻井取心资料、测井和地震资料以及分析化验资料,将下白垩统划分成周期为4～6 Ma的3个沉积层序并总结了层序边界和体系域边界的识别标志.考虑箕状盆地结构、构造活动特征以及沉积物供源方式,分别论述了盆地陡坡、深洼和缓坡的层序地层样式,指出不同地形区的层序地层叠置样式主控因素是有差异的.依据盆地缓坡地形变化带,可以将一个沉积层序细分成低位、湖侵和高位体系域.研究区层序Ⅲ高位和低位体系域富含油气资源,是今后寻找隐蔽圈闭的主要层段。     

填充墙RC框架结构加固方法的研究现状及展望

综述了用于提高填充墙钢筋混凝土(RC)框架结构抗震性能和改善结构损伤模式的几类加固措施,从工艺、加固效果和破坏形式3个角度进行了分析.在建筑结构设计过程中,填充墙通常被视为一种典型的脆性非均质非结构构件,忽视了填充墙与RC框架之间的相互作用.地震调查报告表明,在结构遭受地震作用时,填充墙通常先于钢筋混凝土框架发生破坏,...     

基于立体视觉的砌体房屋模型振动试验研究

针对结构动态响应监测三维变形的需求,研究立体视觉三维测量算法,建立基于结构测面的世界坐标系,得到结构振动响应三维位移公式.研究圆形标识点边缘检测、中心拟合及匹配约束算法,编译基于MATLAB平台的立体视觉结构振动测试分析软件.使用本文集成的立体视觉测量系统完成不同加速度峰值Taft波及El Centro波作用下砌体房屋模型振动台试验,同时测得结构三维位移时程曲线.面内位移时程曲线表明立体视觉方法与位移计数据吻合非常好,证实立体视觉测量方法的有效性.离面位移时程曲线表明砌体房屋模型在地震动作用下发生扭转,且随地震动加速度峰值增大,扭转反应加剧,充分验证立体视觉方法用于监测结构三维振动响应的可靠性及实用性.     

Shaking table testing of an existing masonry building: assessment and improvement of the seismic performance

This paper aims to assess and improve the seismic performance of an existing masonry building with flexible floors, representative of a Portuguese building typology—‘gaioleiro’ buildings. The study involved seismic tests and dynamic identification tests of two models (nonstrengthened and strengthened) in the shaking table. Each model was subjected to several seismic tests with increasing amplitude. Before the first test and after each seismic test, the dynamic identification of the model was carried out, aiming at obtaining their seismic vulnerability curves based on a damage indicator obtained from the decrease of the frequencies of the modes. In the strengthened model, steel elements were used to improve the connection between walls and floors, together with ties in the upper stories. The results show that adopted strengthening technique is effective for reducing the seismic vulnerability of ‘gaioleiro’ buildings, namely for improving the out‐of‐plane behavior of the facades. Copyright © 2013 John Wiley & Sons, Ltd.     

Analytical model for the out‐of‐plane response of vertically spanning unreinforced masonry walls

An analytical model describing the flexural response of vertically spanning out‐of‐plane loaded unreinforced masonry walls is presented in this paper. The model is based on the second‐order Euler‐Bernoulli beam theory and captures important characteristics of the out‐of‐plane response of masonry walls that have been observed in experimental tests and from numerical studies but for which an analytical solution was still lacking: the onset and the evolution of cracking, the peak strength of the out‐of‐plane loaded walls, and the softening of the response due to P ?Δ effects. The model is validated against experimental results, and the comparison shows that the model captures both the prepeak and postpeak response of the walls. From the analytical model of the force‐displacement curve, a formula for the maximum out‐of‐plane strength of the walls is derived, which can be directly applied in engineering practice.     

Practice‐oriented probabilistic seismic performance assessment of infilled frames with consideration of shear failure of columns

The objective of the study presented in this paper is to investigate the effects of masonry infills on the shear demand and failure of columns for the case when reinforced concrete frames with such infills are modeled by means of simplified nonlinear models that are not capable of the direct simulation of these effects. It is shown that an approximate simulation of the shear failure of columns can be achieved through an iterative procedure that involves pushover analysis, post‐processing of the analysis results using limit‐state checks of the components, and model adaptation if shear failure of columns is detected. The fragility parameters and the mean annual frequency of limit‐state exceedance are computed on the basis of nonlinear dynamic analysis by using an equivalent SDOF model. The proposed methodology is demonstrated by means of two examples. It was shown that the strength of the four‐story and seven‐story buildings and their deformation capacity are significantly overestimated if column shear failure due to the effects of masonry infills is neglected, whereas the mean annual frequency of limit‐state exceedance for the analyzed limit states is significantly larger than that estimated for the case if the shear failure of columns is neglected. Copyright © 2012 John Wiley & Sons, Ltd.