竖向荷载下矩形闭合地下连续墙桥梁基础群墙效应研究

矩形闭合地下连续墙基础（简称闭合墙基础）是一种新型的桥梁基础。通过室内模型试验,对闭合墙基础的群墙效率、沉降比等进行了研究,同时探讨了闭合墙墙间距（即内侧边长）对群墙效应的影响。试验中采用了2组不同截面尺寸的模型墙,其中A组模型墙边长小于B组模型墙,墙厚和墙高均相同。试验研究表明,闭合墙与单片墙在相同沉降下的荷载比一般都大于1,B组闭合墙荷载比和群墙效率均大于A组闭合墙;闭合墙与单片墙在相同墙顶应力下的位移比和沉降比基本都大于1,A组闭合墙位移比大于B组闭合墙。在保持墙厚和墙高不变的情况下,适当增大闭合墙基础的内侧边长可以有效地提高群墙效率和承载性能,从而获得更好的经济效益。     

以持续可居性为核心的经济适用房设计

在对低收入家庭的居住现状与居住空间需求的调查研究基础上,结合2008年全国保障性住房设计方案竞赛的回顾与思考,提出社会保障型住宅设计的策略与原则。     

A distributed shear and flexural flexibility model with shear–flexure interaction for R/C members subjected to seismic loading

A beam–column‐type finite element for seismic assessment of reinforced concrete (R/C) frame structures is presented. This finite element consists of two interacting, distributed flexibility sub‐elements representing inelastic flexural and shear response. Following this formulation, the proposed model is able to capture spread of flexural yielding, as well as spread of shear cracking, in R/C members. The model accounts for shear strength degradation with inelastic curvature demand, as well as coupling between inelastic flexural and shear deformations after flexural yielding, observed in many experimental studies. An empirical relationship is proposed for evaluating the average shear distortion of R/C columns at the onset of stirrup yielding. The proposed numerical model is validated against experimental results involving R/C columns subjected to cyclic loading. It is shown that the model can predict well the hysteretic response of R/C columns with different failure modes, i.e. flexure‐critical elements, elements failing in shear after flexural yielding, and shear‐critical R/C members. Copyright © 2008 John Wiley & Sons, Ltd.     

静载荷下黄土地基矩形地下连续墙现场试验研究

采用自平衡测试技术,在国内外首次进行了竖向静载荷作用下黄土地基中矩形地下连续墙现场试验研究,根据测试结果及黄土的物理力学性质,对黄土地基中矩形地下连续墙的荷载传递性状进行了详细分析。结果表明：黄土地基中矩形地下连续墙的承载特性具有端承摩擦桩的性质;墙的承载力由墙侧摩阻力和端阻力共同承担;墙侧摩阻力和端阻力的发挥与墙土的相对位移量及黄土的物理力学性质等因素有关;墙体达到极限荷载时,墙端阻力荷载分担比为40.3 %;各土层墙侧摩阻力随着墙土相对位移的增加而增大,但其增长幅度不等;加载时墙身轴力在加载处最大,随着各土层墙侧摩阻力作用的发挥,墙身轴力随着离荷载箱距离的增加而减小。     

桩（墙）单位侧摩阻力与轴向应变关系的解析解及其应用

根据弹性力学原理,提出了模型筒桩（闭合墙）的简化力学模型。采用半逆解法先求出桩左右侧受均布摩阻力、桩顶受均布荷载两种情况下的应力分量,根据叠加原理得出桩两侧均受相同摩阻力、桩顶受均布荷载情况下的应力分量。据此推导了普通桩基的轴力和侧摩阻力计算式,分析结果表明,该计算式与传统计算方法是一致的。当桩壁两侧受不同大小的侧摩阻力、桩顶受均布荷载时,仍采用叠加原理求得各应力分量,进而求得桩表面处的轴向应变与单位侧摩阻力关系的解析解。通过矩形闭合墙基础模型试验实例,对该解析解的应用方法加以说明。该解析解的求出,为竖向载荷试验中模型筒桩（闭合墙）所量测的内外侧应变进行数据处理提供了理论依据,进而为基础-土相互作用研究提供了真实、准确的试验结果。     

地下连续墙钢筋笼吊装参数的验算与选择

通过对哈尔滨地铁2号线工人文化宫站地下连续墙钢筋笼长度及厚度的研究,工程钢筋笼长度长,厚度小,整体刚度小。介绍了采用15点起吊的吊装技术,并通过对其吊点、钢丝绳、扁担等参数的验算与选择,提供了一种经济、合理、科学、安全的吊装方法,对类似地下连续墙钢筋笼吊装具有一定的指导意义。     

Seismic behavior of variable frequency pendulum isolator

Earthquake performance of a flexible one-story building isolated with a variable frequency pendulum isolator （VFPI） under near-fault and far-field ground motions is investigated. The frictional forces mobilized at the interface of the VFPI are assumed to be velocity dependent. The interaction between frictional forces of the VFPI in two horizontal directions is duly considered and coupled differential equations of motion of the isolated system in the incremental form are solved iteratively. The response of the system with bi-directional interaction is compared with those without interaction. In addition, the effects of velocity dependence on the response of the isolated system are also investigated. Moreover, a parametric study is carried out to critically examine the influence of important parameters on bi-directional interaction effects of the frictional forces of the VFPI. These parameters are： the superstructure time period, frequency variation factor （FVF） and friction coefficient of the VFPI. From the above investigations, it is observed that the dependence of the friction coefficient on relative velocity of the system does not have a noticeable effect on the peak response of the system isolated with VFPI, and that the bi-directional interaction of frictional forces of the VFPI is important and if neglected, isolator displacements will be underestimated and the superstructure acceleration and base shear will be overestimated.     

地下连续墙施工影响应力重分布的数值模拟

对武汉市某超大型超深基坑10幅邻近地连墙跳跃式施工过程进行了三维有限差分数值模拟。数值模拟步骤依次为泥浆护壁成槽开挖、混凝土浇筑及混凝土硬化3个过程。泥浆护壁成槽开挖及混凝土浇筑分别采用常静液压力和变静液压力的方式加载,混凝土的硬化过程采用变弹性模量和泊松比的线弹性实体单元完成。数值计算结果与实测数据吻合较好。对单个跳跃式开挖过程墙上土压力的监测揭示了地下连续墙施工影响应力重分布的变化规律。模拟施工完成后10幅地下连续墙上的土压力值沿墙长度方向随静止土压力值上下波动,波谷出现在槽段连接处附近,波峰接近槽段中心轴,波动幅度大小与土体深度有关。分析表明,泥浆压力、混凝土灌注压力及土压力差值是影响墙后应力重分布波动幅度的主要原因,适当的泥浆重度及合理的注浆方式能避免土体扰动。     

Curvature of Flexibility Matrix for Damage Identification in Legs of Jacket Platforms

In this paper a new nondestructive damage identification method is introduced. The method based on flexibility matrix can be used to detect and locate structm＇al damage and evaluate the severity of damage in legs of jacket platforms by modal parameters of a structure. With the modal data for only the few lower modes in both the intact and damaged states, the one-dimensional and two-dimensional distributed curvatures can be used to analyze damage location and the severity. Instead of directly comparing the curvatures before and ＇after damage, the method here uses modal parameters only in the damaged structure to detect the damage and it consists of three parts. First, ilexibility matrix is obtained by use of the absolute maximum in each column. Second, because the legs of jacket platforms are the pipe-like structure, the circumferential flexibility curvature matrix is obtained by use of the circular curvature. At last, equivalent curvature ratio is defined and the curve meaning equivalent curvature ratio and the severity of damage relationship for one element is given through the data of damage severity from ten percent to ninety percent by numerical simulation. Many existing damage detection methods need two steps, locate the damage firstly and evaluate the severity of the damage. However, the method present- ed! in this paper can locate and then evaluate the severity of damage at the same time. The numerical analysis results in- dicate that the present method is effective, useful and only need the first and the second mode data of the structure.     

地铁换乘站基坑变形流固耦合数值分析研究

地铁换乘站基坑在施工过程中要严格控制其变形及对周边环境产生的影响.尽管流固耦合与非流固耦合分析结果有一定差异,但现有地铁换乘站基坑开挖变形计算中较少考虑流固耦合作用.本文针对济南长途汽车站地铁换乘站进行基坑变形分析,建立了考虑流固耦合的三维有限元模型,根据模拟结果,确定出地连墙最大侧向位移及地面沉降最大值发生的位置,并...