Economic effects of regulating the seismic strengthening of older buildings

The marked increase in the awareness of earthquake risk following the Canterbury earthquakes in New Zealand offered a unique opportunity to investigate the economic effect of disaster-mitigation regulations on the commercial building stock. A difference-in-differences (DD) framework was used to determine whether earthquake risk has been capitalized into the property prices of buildings constructed prior to 1976, as a response to the national policy requiring assessment and strengthening (or demolition) of the existing earthquake-prone building stock. A negative externality is found in the policy announcement on affected (pre-1970s) office and retail buildings which caused office buildings to suffer a 12.5% stigma discount. However, retail properties were less impacted suffering a 2.3% stigma loss. The value of the commercial building stock has been affected by the policy. These findings provide policy-makers with timely evidence as to the economic effects of New Zealand’s earthquake-prone buildings policy. Facing losses in property value and financial responsibility for retrofitting their assets, building owners will be looking for a workable set of regulatory and non-regulatory incentives to encourage disaster risk management and protect the built environment.     

Measurement-based support for post-earthquake assessment of buildings

After a damaging earthquake, assessment of the residual seismic capacity is required for large parts of the building stock. Increased vulnerability of structures together with the threat of immediate aftershocks call for rapid and objective decision making. Structural identification has the potential to reduce parameter-value uncertainties of physics-based models through interpreting measurement data. Significant amounts of uncertainty are associated with the non-linear behaviour of structures during extreme events such as earthquakes. Therefore, a structural identification methodology that accommodates multiple sources of systematic modelling uncertainties is used. Error-domain model falsification (EDMF) enables structural identification through combining damage grades observed by visual inspection with fundamental frequencies that are derived from ambient vibrations. Parametric uncertainties of a hysteretic model are reduced with the two information sources in order to extrapolate the vulnerability of the building regarding future earthquakes. The applicability of the methodology is shown using measurements made on a mixed reinforced-concrete unreinforced-masonry building tested on a shaking table. Based on nonlinear time-history analyses involving single-degree-of-freedom models, EDMF leads to more precise, yet robust, vulnerability predictions of earthquake-damaged buildings when compared with prediction ranges that are obtained without data interpretation.     

A typological classification of the Greek residential building stock

Based on the European Directive on the Energy Performance of Buildings a new regulation framework has recently been implemented in Greece, aiming at the CO₂ emissions reduction caused by the building sector. Given the fact that almost 71% of the Greek buildings were constructed before the implementation of the first Thermal Insulation Regulation (TIR), emphasis must be laid upon the existing building stock. Moreover, 83% of this stock consists of residential buildings, indicating the large potential in energy conservation. In order to plan and promote the respective energy renovation scenarios, a thorough analysis of the Greek building stock has to be carried out, especially regarding the urban built environment. In order to achieve this, a classification of the dominating multifamily building typology is being presented and characteristic examples are being studied.     

基于LEED-NC V4.0材料与资源项的建筑废弃物回收利用

近年来随着我国城市化进程加快,新建和拆迁活动产生了大量的建筑废弃物,因其难以回收而被填埋,由此引发了一系列问题,诸如环境污染、资源浪费和土地占用等。美国绿色建筑评估体系第四版已于2014年实施,其中新建建筑体系适用于新建和旧建筑重大改造项目。LEED通过对材料与资源的评分来鼓励建筑废弃物的回收利用。通过分析第四版LEED新建建筑评估体系的材料与资源评分项,为我国建筑废弃物的回收利用提供一些参考。     

发达国家既有集合住宅再生理论综述

20世纪70年代,二战后困扰发达国家的居住问题已基本得到解决。人们开始反思大规模工业化住宅建设模式,并思考居住环境个性化和品质提升这一新课题。在多样化、解体和不确定的"成熟期"新社会文化背景下,各种建筑与规划设计理论不断涌现,可持续建筑思想逐渐被社会所接受。其中对既有集合住宅再生实践影响较大的理论,如开放建筑/住宅理论、协作式规划设计理论、再生构法理论等得以发展,这些理论和方法对集合住宅的可持续再生产生了积极、广泛的影响。针对这些理论进行了归纳和总结。     

我国城市更新中的类型学思考

城市更新是一个不得不说的话题,也持续地存在着许多问题,大拆大建式的、城市运动式的更新改造已经使中国很多原本极具特色的城市旧区迅速地从地图上消失。本文从中国城市更新中显现出的类型学倾向出发,分析城市形态塑造中类型学的意义,以及在旧城更新中,如何从城市母体与公共建筑两个层面实现更新类型的选择与转换。     

A primer on the building economics of climate change

Climate change will entail new conditions for the construction industry. Knowledge about the implications of climate change on the built environment will be of the utmost importance to the industry in years to come. A building is a ‘long lasting’ durable asset that is changed over time due to exogenously imposed strains and by actions. The built environment has an expected lifetime varying from 60 to more than 100 years. Hence, the building economics of climate change should be treated within a dynamic analytical framework that explicitly allows for changes in the information sets over time. The building stock of the future consists of the building stock of today and of new construction. In the future, parts of the present building stock will be adapted to changes in the environment, while some parts will be kept as they are. Analysis of how building stock is affected by future climate change should handle this diversity. This can be done through the use of a putty-clay model. Uncertainty of what kind of climate regimes will prevail in the future enhances the profitability of actions that increase future flexibility. Hence, the real option approach to building economics is utilized.     

Observations on earthquake resistance of traditional timber-framed houses in Turkey

The aim of this study is to establish the earthquake behaviour of traditional timber-framed houses in Turkey and their technical features to serve as a guide in their conservation. This paper first discusses the destructive effects of changing settlement patterns on the traditional building stock and explores earthquake damage on traditional Turkish buildings, analysing the 1894-?stanbul, 1970-Gediz and finally 1999-Kocaeli earthquakes. A short definition is then provided of timber-framed building methods in Anatolia, and the earthquake damages occurring in them are given. The following section briefly discusses the earthquake behaviour of timber-framed constructions in different countries. The paper concludes with the interpretation of features that increase the earthquake resistance of timber-framed buildings, which are related to the selection of land and the use of the lath and plaster technique, timber lintels, braces and nails.     

Development of building vulnerability functions in subsidence regions from empirical methods

The extraction of ores and minerals by underground mining often causes ground subsidence phenomena. In urban regions, these phenomena may induce small to severe damage to buildings. To evaluate this damage, several empirical and analytical methods have been developed in different countries. However, these methods are difficult to use and compare due to differences in the number of criteria used (from 1 to 12). Furthermore, the results provided by damage evaluation may be significantly different from one method to another. The present paper develops vulnerability functions based on a concept that has been applied in other areas, such as earthquake engineering, and that appears to be a more efficient way to assess building vulnerability in undermined cities. A methodology is described for calculating vulnerability functions in subsidence zones using empirical methods. The first part of the paper focuses on existing empirical methods for damage evaluation, and selected necessary improvements or modifications are justified. The second part focuses on the development of a building typology in subsidence zones and its application in the Lorraine region, where many villages are subject to subsidence problems due to iron-ore mining. The third section describes and discusses the adopted methodology for determining vulnerability and fragility functions or curves. Finally, vulnerability functions are tested and validated with a set of three subsidences that occurred in Lorraine between 1996 and 1999.     

由汶川地震引发对房屋建造过程的思考

结合汶川地震中房屋震害情况,对当前房屋建造过程进行了反思,从建筑安全储备和结构设计优化两方面探讨了结构安全度的问题,并分析了建筑过程中的诚信问题,以期引导工程技术人员增强房屋结构安全意识。