Seismic response of a 40‐storey buckling‐restrained braced frame designed for the Los Angeles region

This study utilized nonlinear response history analysis to compare the seismic demand on three variations of a 40‐storey buckling‐restrained braced frame designed for high seismic hazard in the Los Angeles region. The three designs were referred to as a ‘code‐based design’, based on the 2006 International Building Code, a ‘performance‐based design’, based on criteria published by the Los Angeles Tall Building Design Council (LATBSDC) and a ‘performance‐based design plus’, based on newly developed criteria from The Pacific Earthquake Engineering Research Center (PEER). The response history analysis utilized spectrum‐matched ground motions as well as simulated ground motions for the Puente Hills fault. The spectrum‐matched motions were selected from the Next Generation Attenuation of Ground Motions (NGA) database, which is largely composed of recorded motions and scaled to five hazard levels. The simulated ground motions were broadband signals generated from a moment magnitude (M_w) 7.15 scenario rupture of the Puente Hills fault for two near fault regions and exhibit long period energy content that significantly exceeds the uniform hazard spectrum. Structural performance was assessed in terms of exceedance of a safe inter‐storey drift ratio (IDR). It was seen that the simulated ground motions impose higher IDR demands on the structures than the spectrum‐matched NGA ground motions. Furthermore, the number of instances of exceedance of a safe IDR, considered for this study as IDR = 0.03, is substantially higher for the simulated ground motions, pointing to the importance of considering such motions in the collapse prevention of tall buildings on a site‐specific basis. Copyright © 2010 John Wiley & Sons, Ltd.     

Retrofit of RC frames against progressive collapse using prestressing tendons

This study investigates the effect of prestressing tendons on the progressive collapse performance of a 6‐ and 20‐story reinforced concrete model structures. According to nonlinear static and dynamic analysis results, the analysis model structures turned out to be vulnerable to progressive collapse caused by sudden loss of a first story column. However, the RC structures reinforced by external prestressing tendons along floor girders showed stable behavior against progressive collapse. The retrofit effect increased as the initial tension and cross‐sectional area of tendons increased. The incremental dynamic analyses showed that the seismic performance of the model structure was also enhanced after the retrofit using tendons. Based on analysis results, it was concluded that the retrofit of existing buildings using prestressing tendons could be effective for increasing both progressive collapse resisting capacity and seismic performance of RC framed structures. Copyright © 2011 John Wiley & Sons, Ltd.     

Multidimensional benefit–cost evaluation of asphaltic concrete overlays of rigid pavements

Using the data from a national study in the USA, this study demonstrated a comprehensive and multidimensional pavement treatment evaluation methodology and used the methodology to evaluate the short-term and life cycle cost-effectiveness (CE) of five rigid pavement rehabilitation treatments. Four measures of effectiveness were used in this study: the sudden decrease in surface roughness, treatment service life, increase in average pavement condition over the service life and the area bounded by the performance curve. This study established relationships that quantify the influence of pre-treatment condition on treatment effectiveness. Also, the models were developed to describe the treatment effectiveness as a function of traffic loading and climatic severity. It is seen that at high traffic loading, there is relatively little difference in treatment effectiveness across various climate severities. This study suggests that superior effectiveness of a treatment does not necessarily translate into superior CE. Also, the treatment location was found to influence the relative effectiveness of the treatments. Overall, the results suggest that treatment ‘crack-and-seat and 8-in. asphalt concrete overlay’ is the most cost-effective.     

Robustness of corroded reinforced concrete structures – a structural performance approach

The aim of this work is to provide new contributions in order to define more accurately the structural robustness concept, particularly when applied to corroded reinforced concrete (RC) structures. To fulfil such a task, several robustness indicators are analysed and discussed with special emphasis on structural-performance-based measures. A new robustness definition and a framework are then proposed for its analysis, based on the structural performance lost after damage occurrence. The competence of the proposed methodology is then tested comparing the robustness of two RC foot bridges under corrosion. The damage considered is the longitudinal reinforcement corrosion level, and load carrying capacity is the structural performance evaluated. In order to analyse corrosion effects, a finite element (FE) based on a two-step analysis is adopted. In the first step, a cross-section analysis is performed to capture phenomenons such as expansion of the reinforcement due to the corrosion products accumulation; damage and cracking in the reinforcement surrounding concrete; steel–concrete bond strength degradation; effective reinforcement area reduction. The results obtained are then used to build a 2D structural model, in order to assess the maximum load carrying capacity of the corroded structure. For each foot bridge, robustness is assessed using the proposed methodology.     

A framework for identification and representation of client requirements in the briefing process

The briefing process is critical to the successful delivery of construction projects. Although a number of briefing guides have been developed, attempting to address the problems of briefing, they are often criticized as being too general and implicit. This paper describes a structured framework for identifying and representing client requirements (CRs) in the briefing process. It integrates the value management (VM) methodology with function analysis system technique (FAST) and functional performance specification (FPS) to enable the client organization and project team to systematically identify, clarify and clearly represent CRs in the briefing process. It comprises four interrelated phases: preparation, information, analysis and evaluation. This paper starts with a critical review of previous work in briefing and function analysis, followed by an introduction to the research methodology and detailed illustration of the proposed framework. The use of this framework can facilitate and lead to systematic identification and clarification of client requirements and the formation of a more precise and explicit representation of these requirements. The limitations of the approach are also discussed in the paper.     

A web‐based performance assessment system for environmental protection: WePass

In response to the increasing public concern over the effects of construction waste on the environment, a performance assessment system has been designed to provide an instant, online assessment of how well a construction site performs environmentally, e.g. measuring the level of pollution generated from a construction site. Through the use of both Internet and database technologies, it is possible to collect and present data that are essential for environmental management online. To achieve this, a set of environmental performance parameters was derived through a postal questionnaire survey and interviews with experts in the field. A conceptual framework was developed, of which the key components were: template, knowledge base, output data and benchmark group. In combination, these factors provide a system that enables speedy assessment and effective management of environmental performance on construction sites, hence prompt decisions can be made and corrective actions can be taken before potential hazards turn into real disasters.     

Predicting construction firm performance: an empirical assessment of the differential impact between industry‐ and firm‐specific factors

It is obvious that the performance of firms hinges upon the dynamics of both industry‐ and firm‐specific factors. A less obvious, and perhaps a more important, line of inquiry is that to the extent that they have a bearing on firm performance, how much do these two groups of factors respectively predict firm performance? To date, performance differences among construction firms that stem from industry‐ and firm‐specific differential effect has remained largely unexplored. Using a dataset comprising 526 firms across various construction‐related sectors, the sector‐by‐sector firm performance variation that is attributable to the heterogeneity of both industry‐ and firm‐specific characteristics was empirically examined. That statistically significant results of different effect sizes are found indicates that although these factors are often assumed to be intertwined it is possible to study their respective impact on firm performance. Future studies could usefully replicate and extend this study to construction firms in other countries to further investigate what drives firm performance under different national, industry and firm contexts.     

Project affinity: the role of emotional attachment in construction projects

Although a wide range of human and organizational factors have been found to be important in the operation of projects, those determined by cultural variables are less well defined. One such influence concerns the notion of ‘project affinity’, the commitment and attachment by stakeholders and participants to projects and their outcomes. The temporal nature and transient involvement context provided by construction projects arguably presents a climate in which many participants are less likely to display commitment to its goals. This note is concerned with the issue of whether an attachment to a project's goals or to the completed product can lead to improved commitment among those involved. The concept of project affinity was developed in the course of a case study investigation in which operatives' attitudes towards the construction of a cancer research facility were explored. Because of the contribution of the facility to the future care of cancer sufferers, the concept of project affinity proved helpful in understanding a factor that appeared to be influencing the commitment of those involved. The results suggest a complementary concept to that of ‘project chemistry’ (c.f. Nicolini, 2002 Nicolini, D. 2002. In search of ‘project chemistry’.. Construction Management and Economics, 20: 167–77.  ).     

KVAM: model for measuring knowledge management performance of engineering community of practice

The research presents the development of the knowledge value‐adding model (KVAM) for quantitative performance measurement of the community of practice (CoP) of the knowledge management system (KMS) in an A/E consulting firm. The proposed KVAM combines several existing KM theories including knowledge creation spiral, knowledge chain model, and knowledge value added theory to form a process‐level model for measuring the performance of a generic community of practice (CoP). Case study results show that the proposed KVAM provides KM managers with a useful tool not only to monitor the performance of a CoP and its members but also to plan an effective strategy for performance improvement. Unlike the traditional organizational‐level approaches, the proposed KVAM was concluded to better reflect the actual values solely generated by the KMS rather than other management factors.     

Structural frame selection: case studies of hybrid concrete frames

Hybrid concrete construction (HCC) uses a combination of in-situ and precast concrete and is an example of ‘mixed’ construction, which is the term for an innovative combination of different materials or framing methods. Examples of HCC exist in many countries to fulfil varying structural requirements, so it is not clear why HCC is not better used in the UK. Research was undertaken to gain a better understanding of the selection and use of HCC. Two case study projects were investigated to explore decision-making criteria, the roles of project participants and the challenges particular to HCC. The findings suggest that HCC is selected when measurable cost or programme advantages are not the most important criteria, but where other factors such as satisfying architectural requirements (finish, colour, etc.) or operational demands (such as internal comfort or maintenance) are critical. In both cases, clients and architects were found to be the most influential team members in the frame-selection process.

La construction en béton hybride (HCC) utilise une combinaison de béton in situ et de béton précoulé; c'est un exemple de ‘construction mixte’; cette expression définit une combinaison innovante de différents matériaux et méthodes de coffrage. Il existe des exemples de HCC dans de nombreux pays qui répondent à différentes exigences structurales; on peut donc difficilement expliquer pourquoi la HCC n'est pas mieux utilisée au Royaume-Uni. Des recherches ont été entreprises pour mieux comprendre les choix et les usages de la HCC. Deux études de cas ont été engagées, l'objectif étant d'explorer les critères décisionnels, le rôle des participants à ces projets et les défis particuliers propres à la HCC. Les résultats laissent à penser que la HCC est retenue lorsque le coût mesurable ou les avantages du programme ne sont pas les critères les plus importants et lorsque d'autres facteurs comme la réponse aux exigences architecturales (finition, couleur, etc.) ou d'autres exigences opérationnelles (comme le confort intérieur ou la maintenance) sont critiques. Dans les deux cas, les clients et les architectes sont apparus comme les membres les plus influents des équipes lors du processus de sélection du cadre.

Mots clés: processus de conception, construction en béton hybride, construction mixte, critères de performances, cadre structural