Cyclic testing of unreinforced masonry walls in two‐way bending

An experimental programme was conducted in which eight full‐scale unreinforced masonry walls were subjected to cyclic face loading using a system of airbags. Of the eight walls, six contained a window opening and four were subjected to vertical pre‐compression. Combined supports at the vertical and horizontal edges ensured that under face loading the walls underwent two‐way bending. The test walls were found to possess good post‐peak strength and displacement capacity as well as reasonable energy dissipation characteristics. Significant strength and stiffness degradation and non‐symmetry of strength in the positive and negative displacement directions were also evident. Discussion of the causes of the aforementioned trends and their implications towards the seismic response of masonry walls is provided. Copyright © 2006 John Wiley & Sons, Ltd.     

Multi‐scale modelling approach for the pushover analysis of existing RC shear walls—Part I: Model formulation

This work focuses on the modelling issues related to the adoption of the pushover analysis for the seismic assessment of existing reinforced concrete (RC) structures. To this purpose a prototype reference structure, one of the RC shear walls designed according to the multi‐fuse concept and tested on shaking table for the CAMUS project, is modelled at different levels of refinement. The meso‐scale of a stiffness‐based fibre element and the micro‐scale of the finite element (FE) method are herein adopted; in the latter separate elements are adopted for the concrete, the steel and the steel–concrete interface. This first of the two companion papers presents in detail the wall under study, illustrating the design philosophy, the geometry of the wall, the instrumentation set‐up and the test programme. The two modelling approaches are then described; the most important points in terms of element formulation and constitutive relations for materials are presented and discussed for each approach, in the light of the particular design of the wall and of its experimental behaviour. Copyright © 2007 John Wiley & Sons, Ltd.     

Numerical modelling of clast rotation during soft-sediment deformation: a case study in Miocene delta deposits

A numerical model for a rotated clast in a sedimentary matrix is presented, quantifying the deformation in associated soft-sediment deformation structures. All the structures occur in a southwards prograding deltaic sequence within the Miocene Ingering Formation, deposited at the northern margin of the Fohnsdorf Basin (Eastern Alps, Austria). Debris flow and pelitic strata contain boudins, pinch-and-swell structures, ptygmatic folds, rotated top-to-S reverse faults and rigid clasts, developed under different stress conditions within the same layers. The deformation around a 24×10 cm trapezoid-shaped rigid clast, resembling the δ-clast geometry in metamorphic rocks, has been modelled using a 2D finite element modelling software. Under the chosen initial and boundary conditions the rotational behaviour of the clast mainly depends on the proportions of pure and simple shear; best fitting results were attained with a dominantly pure shear deformation (~65–85%), with stretching parallel and shortening normal to the bedding. In this specific model set-up, the initial sedimentary thickness is reduced by 30%, explained by stretching due to sediment creeping and compaction. The high amount of pure shear deformation proposed is compatible with the observed layer-parallel boudinage and pinch-and-swell structures. Rotated faults and ptygmatic folds were caused by the minor component of bedding-parallel simple shear.     

水泥搅拌桩挡土墙墙顶位移的修正算法

对水泥搅拌桩挡土墙的水平位移计算进行了探讨。以刚性桩法为基础理论和计算模型、弹性抗力法的计算结果为挠曲修正,首次提出一种既便于手算,又能考虑墙身挠曲变形的墙顶位移修正算法。     

Revit在房产测绘中的应用

随着测绘理论的不断发展及各种新技术和新仪器的开发，房产测绘技术也在不断发展。目前国家政策对BIM的大力支持，势必造成传统信息化测绘的巨大变革。Revit作为Autodesk主打的BIM解决方案软件，在房屋建筑设计中广泛应用。但是目前市场上还缺乏针对Revit中的图纸进行快速面积测算的软件。本文对Revit工具集技术在房产测绘中的应用进行了讨论，并给出了一个导出墙中线的开发实例。     

Assessment of strut forces for braced excavation in clays from numerical analysis and field measurements

One important consideration in the design of a braced excavation system is to ensure that the structural bracing system is designed both safely and economically. The forces acting on the struts are often determined using empirical methods such as the Apparent Pressure Diagram (APD) method developed by Peck (1969). Most of these empirical methods that were developed from either numerical analysis or field studies have been for excavations with flexible wall types such as sheetpile walls. There have been only limited studies on the excavation performance for stiffer wall systems such as diaphragm walls and bored piles. In this paper, both 2D and 3D finite element analyses were carried out to study the forces acting on the struts for braced excavations in clays, with focus on the performance for the stiffer wall systems. Subsequently, based on this numerical study as well as field measurements from a number of reported case histories, empirical charts have been proposed for determining strut loads for excavations in stiff wall systems.     

Numerical investigation into the failure of a micropile retaining wall

The paper presents a numerical investigation on the failure of a micropile wall that collapsed while excavating the adjacent ground. The main objectives are: to estimate the strength parameters of the ground; to perform a sensitivity analysis on the back slope height and to obtain the shape and position of the failure surface. Because of uncertainty of the original strength parameters, a simplified backanalysis using a range of cohesion/friction pairs has been used to estimate the most realistic strength parameters. The analysis shows that failure occurred because overestimation of strength and underestimation of loads.     

悬臂抗滑桩静、动力学性能试验的全过程

基于悬臂抗滑桩治理堆积型滑坡的静、动力离心模型试验,利用土压力传感器、应变片以及加速度传感器采集到的试验数据,研究了静、动力条件下抗滑桩的受力特性,分析了被治理滑坡的地震响应特征。结果表明：静、动力条件下桩后土压力以及桩身弯矩的分布规律均不同;桩后静土压力大于地震动引起的动土压力,但桩身静弯矩远小于地震动引起的动弯矩;桩后动土压力和动弯矩随峰值地震动的增大而增大;地震作用时土压力和桩身弯矩最大值的作用点低于静力的;滑体加速度响应存在浅表放大效应和高程放大效应,坡肩附近的波型转化现象显著,抗震设计时应予以重视。     

Shaking table model test and engineering practice of a new gypsum-adobe walls dwelling in Xinjiang autonomous region, China

The paper introduces a new type of green building which suits for the construction of rural dwellings in Xinjiang, China. Results of the shaking table test on building model show that the single-layer gypsum-adobe structure has better seismic performance. And it also analyzes the construction features and engineering practice, which means that it is significant to extend this type of building to the drier regions in China.     

RPC面层加固约束空斗墙参数分析和抗震承载力研究

为弥补空斗墙抗震性能差和发挥活性粉末混凝土(RPC)的超高韧性,对1片未加固处理的空斗墙和2片由RPC面层加固处理的空斗墙分别进行拟静力试验,并结合有限元对三组试验进行参数分析。得出影响墙体抗震性能的主要因素有:墙体构造柱尺寸、轴压比、RPC单双面加固以及面层加固厚度。根据试验和有限元所得到的破坏特征,结合圈梁-构造柱对墙体的约束作用,引入等效受压斜撑模型,并量化圈梁-构造柱对墙体约束效应。基于圈梁-构造柱与墙体、RPC面层与被约束的墙体的协同受力特性,建立约束墙体及面层加固体墙的抗剪承载力的计算式。