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.     

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。     

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.     

Scenario loss earthquake damageability analysis

The financial vulnerability of properties is often determined for specific, scenario earthquakes. The influence of three separate issues on damage to two portfolios are explored: specification of the earthquake considered; specification of the resulting site ground motions; and characterization of the resulting building damageability. A site in San Francisco is considered for a range of building vulnerabilities from very low to very high. Scenario losses are developed for the maximum credible earthquakes on the San Andreas and Hayward faults. Several different assumptions are used to characterizing these earthquakes, including single magnitude values and logic tree characterizations, and the ground motion at the site, including the average value and a probability distribution. Building damageability estimates are made for each different characterization of the scenario earthquake using median, average and 10% exceedance measures of damageability. The results shown how significant the selection of the particular scenario magnitude, site ground motion characterization, and damageability values are to the final results; high values can be as much as four times the low values, all assuming exactly the same earthquake environment and building damageability. It is recommended that the scenario be defined in terms of a logic tree formulation of possible earthquakes to assure that all possible magnitudes are considered, that a probability distribution be used to characterize the building site's ground motion, and that the damageability estimation procedure fully considers uncertainties in both the site ground motion and building damageability in a consistent statistical manner. Copyright © 1999 John Wiley & Sons, Ltd.     

Confined masonry as practical seismic construction alternative–the experience from the 2014 Cephalonia Earthquake

During August 1953 three strong earthquakes of magnitude ranging from 6.3 to 7.2 shook the Ionian Island of Cephalonia (Kefalonia), Greece, and destroyed almost the entire building stock of the Island which consisted primarily of traditional unreinforced masonry (URM) houses. The authorities went on to restructuring of the building stock, using a structural system that is most like what is known today as confined masonry. They designed about 14 types of one- to two-storey buildings providing the engineers with detailed construction plans. These buildings are known as “Arogi” buildings (Arogi in Greek meaning Aid). On the 24th of January and 3rd of February 2014, two earthquakes of magnitude 6.1 and 6.0 struck the island, causing significant soil damages, developing excessively high ground accelerations. Surprisingly, no damage was reported in the “Arogi” buildings. The seismic behavior of the buildings is examined by FEM linear analysis and it is compared to that of URM structures. Computed results illustrate that the displacements of identical URM buildings would be about twice the magnitudes observed in the corresponding “Arogi” ones, with the implication that the earthquake sequence of 2014 would have caused critical damage should the type of structure be of the URM type. Furthermore, it is illustrated that this low cost alternative method of construction is a very effective means of producing earthquake resilient structures, whereas further reduction of seismic displacement may be achieved in the order of 50% with commensurate effects on damage potential, when reinforced slabs are used to replace the timber roofs.     

组合式住宅的技术创新与发展

全球范围内，人们对经济适用房屋一直有极大需求，但沿用传统建造方式，则无法满足人们对其质量，数量、进度、性能和价格上的要求。根据英国、欧洲，美国和日本等西方发达国这的经验，组合式房屋是解决此问题的最好方法之一。     

新加坡组屋的规划建设及其启示

自1960年代以来,新加坡就实施了"居者有其屋"的住房政策,组屋规划建设成就斐然。文章介绍了新加坡有关住房的政策和组屋类型,论述了新加坡组屋的规划、建筑设计以及更新、改造等特点,由此得出新加坡组屋规划建设经验对我国未来住宅建设的启示。     

既有建筑宜居改造及功能提升调查分析

在我国住房建设的总体趋势—从增量向增存并举转变的背景下,建筑宜居改造及功能提升成为了近来建筑业的一项持续性热点工作。对我国既有居住建筑改造与功能提升的3 个发展阶段进行了总结分析,结合中国建筑业协会2019 年做的行业调研,重点研究了建筑宜居改造及功能提升的政策环境、改造需求,并通过调研情况对建筑宜居改造进行了共性分析研究,针对性地提出了制定既有居住建筑共担共建投资组织方式和建立科学评估、内容可选、自主决策的菜单改造模式政策性建议。     

中国国家博物馆加固改造工程保护性拆除施工

与一般的破坏性拆除不同,建筑加固改造工程中的拆除属于保护性拆除,拆除过程必须保证原建筑的结构安全.拆除局部构件时,不允许对相邻的非拆除构件造成结构性损伤,一般应采取对相邻构件不产生不良影响的静力拆除.详细阐述了中国国家博物馆改造工程中的拆除施工方法及安全技术措施.     

Post-war urban renewal and demolition fluctuations in Sweden

In the decades following the Second World War, Swedish cities experienced extensive urban renewal projects that continue to shape the country’s contemporary built environment. Many Swedish cities saw large-scale demolitions starting in the 1950s. The demolitions increased during the 1960s and 1970s, when the government implemented the so-called Million Programme (1965–1974). The declared target of the housing policy was to raise housing standards, create healthy living conditions and lessen the housing shortage through the construction of modern housing. In the 1980s, the preservation and modernization of dwellings replaced the clearance policy. The 1990s brought a new demolition wave, which subsided in the 2000s. This paper reviews the renewal processes and various phases of demolition activity in Swedish post-war cities from the perspective of housing policy and planning. The research analysis is based on the literature and statistics.     

Greening heritage housing: understanding homeowners’ renovation practices in Australia

In the context of recent policy moves to reduce environmental impacts, it is argued that significant improvements are required to heritage housing stock. Existing housing stock is recognised in planning/legislation for some form of protection based upon its heritage significance. Although renovation of existing dwellings is the principal means promoted to reduce energy and associated environmental emissions, little attention has been given to how this is achieved in practice. This paper joins an emerging body of work that draws on social practice theory, as an alternative to rational and behaviourist perspectives, to investigate renovation practices in heritage housing. Based on analysis of interviews with homeowners, this paper discusses the common social understandings associated with heritage buildings, environmental sustainability, and comfort, and how these intersect in home-renovation. The study explores how households balance emerging needs for environmental sustainability with retaining heritage significance. Questions are raised as to the extent to which renovations can contribute to objectives for reducing energy use and emissions, and implications are drawn for future policy approaches regarding the attainment of more sustainable practices.     

Homogenous homes of Finland: ‘standard’ flats in non-standardized blocks

Several authors have successfully created and employed vintage cohorts and housing typologies in research addressing energy renovation needs in the existing dwelling stock. This paper suggests that the idea of types would be useful in creating living quality-related renovation and adaptation concepts for homes. These concepts could be used for increasing the accessibility and individuality of flats and easing life in cramped conditions by means of design. Therefore, the study tests the approach by examining the plan design of flats in one cohort: the Finnish 1960–80s' dwelling stock. A total of 320 apartment blocks with 8745 flats in 51 cities are examined. The study identifies 18 different types of flats, which are based on 10 basic layouts, representing over 80% of all flats. Although the housing production of this era was characterized by cost-efficiency and industrialized prefabrication technologies, the result can be deemed somewhat surprising. This is because the building layouts were never standardized in Finland: only the production technology was standardized. The identified flat types are estimated to cover as much as one-third of all existing Finnish flats. These findings provide future opportunities for creating new mass-tailored renovation concepts.     

Application of BCP-2007 and UBC-97 in seismic vulnerability assessment of gravity designed RC buildings in Pakistan

Recent earthquakes in Pakistan (Kashmir 2005, Balochistan 2008, and Balochistan 2013) revealed the vulnerability of existing building stock and the deficiencies in the then prevalent Pakistan Seismic Code (PSC-86 (1986)). This study investigates, through an analytical framework, the seismic vulnerability of these and other such buildings, in accordance with the newly developed Building Code of Pakistan – Seismic Provisions 2007 (BCP-SP 07). Detailed failure mode is presented for buildings designed as per the new code. Collapse of structures is predicted for only 8% increase in PGA after moderate damage. A previously developed method, based on Eurocode-8 (2004), is used as baseline. A deficient reinforced concrete frame, typical to local building practices, is analyzed and assessed for vulnerability using the BCP-SP 07 (2007) framework. A comparison is drawn for the same building, based on Eurocode-8 (2004). Derived vulnerability curves show that the previous framework overestimated the damage and hence the vulnerability. Comparison of vulnerability parameters with previous studies show slight difference in performance of buildings.