福州软土地区上浅基的岩土工程问题

软土在我国沿海一带分布很广,如渤海湾,天津塘沽,长江三角洲,浙江、珠江三角洲,以及福建的沿海地区都存在海相或相沉积的软土,具有松软,孔隙比大、压缩性高和强度低的特点。本文提出软土浅基的建筑病害,处理方法,以及对软土上浅基设计的几点建议,     

Ductility demands on buckling-restrained braced frames under earthquake loading

Accurate estimates of ductility demands on buckling-restrained braced frames (BRBFs) are crucial to performance-based design of BRBFs. An analytical study on the seismic behavior of BRBFs has been conducted at the ATLSS Center, Lehigh University to prepare for an upcoming experimental program. The analysis program DRAIN-2DX was used to model a one-bay, four-story prototype BRBF including material and geometric nonlinearities. The bucklingrestrained brace (BRB) model incorporates both isotropic and kinematic hardening. Nonlinear static pushover and timehistory analyses were performed on the prototype BRBF. Performance objectives for the BRBs were defined and uscd to evaluate thc time-history analysis results. Particular emphasis was placed on global ductility demands and ductility demands oa the BRBs. These demands were compared with anticipated ductility capacities. The analysis results, along with results from similar previous studics, are used to evaluate the BRBF design provisions that have been recommended for codification in the United States. Thc results show that BRB maximum ductility demands can be as high as 20 to 25. These demands significantly exceed those anticipated by the BRBF recommended provisions. Results from the static pushover and timehistory analyses are used to demonstrate why the ductility demands exceed those anticipated by the recommended provisions.The BRB qualification testing protocol contained in the BRBF recommended provisions is shown to be inadequate because it requires only a maximum ductility demand of at most 7.5. Modifications to the testing protocol are recommended.     

软土流变模型及在建筑物纠偏工程中的应用

根据地基应力解除法纠偏方法原理和软土的变形机理,建立了土体非线性弹-粘弹流变本构模型,并将其成功运用于软粘土地基应力解除法纠偏工程实践.结合某6层住宅楼的倾斜扶正过程,运用所建的本构模型和有限元技术进行了全过程的数值模拟,揭示了建筑物倾斜过程和扶正过程中地基应力-应变的变化规律,并预测了纠偏施工后建筑物的附加沉降量,所得结果与实测结果有较好的吻合.研究表明,土的流变特性对软土地基建筑物的纠偏实践有明显的影响,在实际工程中应予以充分考虑.     

大型火力发电厂钢筋混凝土横向框排架主厂房动力特性试验研究

对1／7大型火力发电厂三跨三榀钢筋混凝土横向框排架子空间模型，分别用激振法和柔度矩阵法进行模型结构动力特性试验，研究该结构的前三阶周期和振型，同时根据拟动力试验中结构的位移反应，求得在不同破损阶段模型结构的动力特性，最后根据相似关系得出原型结构的动力特性。     

Seismic behavior of asymmetric RC wall buildings: principles and new deformation‐based design method

The seismic design of multi‐story buildings asymmetric in plan yet regular in elevation and stiffened with ductile RC structural walls is addressed. A realistic modeling of the non‐linear ductile behavior of the RC walls is considered in combination with the characteristics of the dynamic torsional response of asymmetric buildings. Design criteria such as the determination of the system ductility, taking into account the location and ductility demand of the RC walls, the story‐drift demand at the softer (most displaced) edge of the building under the design earthquake, the allowable ductility (ultimate limit state) and the allowable story‐drift (performance goals) are discussed. The definition of an eccentricity of the earthquake‐equivalent lateral force is proposed and used to determine the effective displacement profile of the building yet not the strength distribution under the design earthquake. Furthermore, an appropriate procedure is proposed to calculate the fundamental frequency and the earthquake‐equivalent lateral force. A new deformation‐based seismic design method taking into account the characteristics of the dynamic torsional response, the ductility of the RC walls, the system ductility and the story‐drift at the softer (most displaced) edge of the building is presented and illustrated with an example of seismic design of a multi‐story asymmetric RC wall building. Copyright © 2005 John Wiley & Sons, Ltd.     

Effect of Overstrength on the Seismic Behaviour of Multi-Storey Regularly Asymmetric Buildings

In past years, seismic response of asymmetric structures has been frequently analysed by means of single-storey models, because of their simplicity and low computational cost. However, it is widely believed that use of more realistic multi-storey models is needed in order to investigate effects of some system characteristics (such as overstrength, higher modes of vibration, etc.) that make behaviour of multi-storey schemes different from that of single-storey systems. This paper examines effects of the overstrength in element cross-sections on the seismic behaviour of multi-storey asymmetric buildings. It is shown that in actual buildings this characteristic, which is sometimes very variable both in plan and along the height of the building, may lead to distributions of ductility demands different from those expected according to the results from single-storey models. Consequently, torsional provisions, which aim at reducing ductility demands of single-storey asymmetric systems to those of the corresponding torsionally balanced systems, should be re-checked in light of the behaviour of realistic multi-storey buildings.     

制图综合中道路与建筑物的移位研究

针对地图中道路与建筑物的具体冲突问题,分析了移位的约束条件,阐述移位算法的发展历史,并对其算法进行了分析与研究,最后设计了解决道路与建筑物具体冲突问题的移位方案。     

A hybrid method for the vulnerability assessment of R/C and URM buildings

The methodology followed by the Aristotle University (AUTh) team for the vulnerability assessment of reinforced concrete (R/C) and unreinforced masonry (URM) structures is presented. The paper focuses on the derivation of vulnerability (fragility) curves in terms of peak ground acceleration (PGA), as well as spectral displacement (s _d), and also includes the estimation of capacity curves, for several R/C and URM building types. The vulnerability assessment methodology is based on the hybrid approach developed at AUTh, which combines statistical data with appropriately processed (utilising repair cost models) results from nonlinear dynamic or static analyses, that permit extrapolation of statistical data to PGA’s and/or spectral displacements for which no data are available. The statistical data used herein are from earthquake-damaged greek buildings. An extensive numerical study is carried out, wherein a large number of building types (representing most of the common typologies in S. Europe) are modelled and analysed. Vulnerability curves for several damage states are then derived using the aforementioned hybrid approach. These curves are subsequently used in combination with the mean spectrum of the Microzonation study of Thessaloniki as the basis for the derivation of new vulnerability curves involving spectral quantities. Pushover curves are derived for all building types, then reduced to standard capacity curves, and can easily be used together with the S _d fragility curves as an alternative for developing seismic risk scenarios.     

Macroseismic and mechanical models for the vulnerability and damage assessment of current buildings

The European Commission funded the RISK-UE project in 1999 with the aim of providing an advanced approach to earthquake risk scenarios for European towns and regions. In the framework of Risk-UE project, two methods were proposed, originally derived and calibrated by the authors, for the vulnerability assessment of current buildings and for the evaluation of earthquake risk scenarios: a macroseismic model, to be used with macroseismic intensity hazard maps, and a mechanical based model, to be applied when the hazard is provided in terms of peak ground accelerations and spectral values. The vulnerability of the buildings is defined by vulnerability curves, within the macroseismic method, and in terms of capacity curves, within the mechanical method. In this paper, the development of both vulnerability and capacity curves is presented with reference to an assumed typological classification system; moreover, their cross-validation is presented. The parameters of the two methods and the steps for their operative implementation are provided in the paper.     

SuperMap Object在地震灾害预估中应用浅析

用基于易损性矩阵基础上的城市震害预估方法，计算调整损失比后的经济损失，其中包括等震线模型、城市震害模型及建筑物直接经济损失模型等的设计与实现，并针对我国城市的具体情况，编制了一套《城市震害预估及房屋易损性矩阵数据库实时更新软件》，为我国震害预估技术的深层次开发打下坚实的基础。