The Experts below are selected from a list of 61833 Experts worldwide ranked by ideXlab platform
Kenneth J. Elwood - One of the best experts on this subject based on the ideXlab platform.
-
understanding post earthquake decisions on multi storey Concrete Buildings in christchurch new zealand
Bulletin of Earthquake Engineering, 2017Co-Authors: Frederic Marquis, Kenneth J. Elwood, Jenna Jihyun Kim, Stephanie E ChangAbstract:The 2010–2011 Canterbury earthquakes, which involved widespread damage during the February 2011 event and ongoing aftershocks near the Christchurch Central Business District, left this community with more than $NZD 40 billion in losses (~20 % GDP), demolition of approximately 60 % of multi-storey Concrete Buildings (3 storeys and up), and closure of the core business district for over 2 years. The aftermath of the earthquake sequence has revealed unique issues and complexities for the owners of commercial and multi-storey residential Buildings in relation to unexpected technical, legal, and financial challenges when making decisions regarding the future of their Buildings impacted by the earthquakes. The paper presents a framework to understand the factors influencing post-earthquake decisions (repair or demolish) on multi-storey Concrete Buildings in Christchurch. The study, conducted in 2014, includes in-depth investigations on 15 case-study Buildings using 27 semi-structured interviews with various property owners, property managers, insurers, engineers, and government authorities in New Zealand. The interviews revealed insights regarding the multitude of factors influencing post-earthquake decisions and losses. As expected, the level of damage and repairability (cost to repair) generally dictated the course of action. There is strong evidence, however, that other variables have significantly influenced the decision on a number of Buildings, such as insurance, business strategies, perception of risks, building regulations (and compliance costs), and government decisions. The decision-making process for each building is complex and unique, not solely driven by structural damage. Furthermore, the findings have put the spotlight on insurance policy wordings and the paradoxical effect of insurance on the recovery of Christchurch, leading to other challenges and issues going forward.
-
Collapse Probability of Existing Concrete Buildings: The Evolution of Seismic Rehabilitation in North America
Performance-Based Seismic Engineering: Vision for an Earthquake Resilient Society, 2014Co-Authors: Kenneth J. Elwood, Majid Baradaran Shoraka, Tony YangAbstract:Existing reinforced Concrete Buildings lacking details for ductile response during earthquake shaking represent a significant life safety risk in high seismic zones around the world. The poor seismic performance of these non-ductile Concrete Buildings is evident from recent earthquakes in Chile, New Zealand and Japan. Seismic rehabilitation of these existing Buildings plays an important role in reducing urban seismic risk; however, with the massive inventory of existing Concrete Buildings and the high costs of seismic rehabilitation , it is necessary to start by identifying and retrofit ting those Buildings which are most vulnerable to collapse. Numerous sources of uncertainty complicate the ability to identify Buildings which are vulnerable to collapse. For this reason, it is important to develop estimates of collapse probability to account for all significant sources of uncertainties. This chapter will introduce the concept of collapse indicators , design and response parameters that are correlated with “elevated” collapse probability. The methodology for identifying collapse indicators is based on results of comprehensive collapse simulations. Appropriate collapse indicators and corresponding limits are evaluated by seeking trends between probability of collapse and collapse indicators . This chapter will discuss significant challenges which pose a barrier to the assessment of collapse indicators that are applicable for the wide range of existing Concrete Buildings.
-
Seismic loss estimation of non‐ductile reinforced Concrete Buildings
Earthquake Engineering & Structural Dynamics, 2012Co-Authors: M. Baradaran Shoraka, Tony Y. Yang, Kenneth J. ElwoodAbstract:SUMMARY Non-ductile reinforced Concrete Buildings represent a prevalent construction type found in many parts of the world. Due to the seismic vulnerability of such Buildings, in areas of high seismic activity non-ductile reinforced Concrete Buildings pose a significant threat to the safety of the occupants and damage to such structures can result in large financial losses. This paper introduces advanced analytical models that can be used to simulate the nonlinear dynamic response of these structural systems, including collapse. The state-of-the-art loss simulation procedure developed for new Buildings is extended to estimate the expected losses of existing non-ductile Concrete Buildings considering their vulnerability to collapse. Three criteria for collapse, namely first component failure, side-sway collapse, and gravity-load collapse, are considered in determining the probability of collapse and the assessment of financial losses. A detailed example is presented using a seven-story non-ductile reinforced Concrete frame building located in the Los Angeles, California. Copyright © 2012 John Wiley & Sons, Ltd.
-
Seismic loss estimation of non-ductile reinforced Concrete Buildings
Earthquake Engineering & Structural Dynamics, 2012Co-Authors: M. Baradaran Shoraka, Tony Yang, Kenneth J. ElwoodAbstract:SUMMARY Non-ductile reinforced Concrete Buildings represent a prevalent construction type found in many parts of the world. Due to the seismic vulnerability of such Buildings, in areas of high seismic activity non-ductile reinforced Concrete Buildings pose a significant threat to the safety of the occupants and damage to such structures can result in large financial losses. This paper introduces advanced analytical models that can be used to simulate the nonlinear dynamic response of these structural systems, including collapse. The state-of-the-art loss simulation procedure developed for new Buildings is extended to estimate the expected losses of existing non-ductile Concrete Buildings considering their vulnerability to collapse. Three criteria for collapse, namely first component failure, side-sway collapse, and gravity-load collapse, are considered in determining the probability of collapse and the assessment of financial losses. A detailed example is presented using a seven-story non-ductile reinforced Concrete frame building located in the Los Angeles, California. Copyright © 2012 John Wiley & Sons, Ltd.
-
Guide for seismic rehabilitation of Concrete Buildings: Summary of future changes
Improving the Seismic Performance of Existing Buildings and Other Structures, 2009Co-Authors: Halil Sezen, J. Dragovich, W. Ghannoum, L. N. Lowes, Sergio F. Breña, Kenneth J. ElwoodAbstract:This paper summarises improvements to the ASCE/SEI 41 Concrete provisions considered for implementation in the new ACI 369 Guide for Seismic Rehabilitation of Existing Concrete Buildings. The paper is intended to inform the structural engineering community on the approach being taken by ACI 369 to provide engineers with the latest modeling approaches and acceptance criteria for the assessment and rehabilitation of existing Concrete Buildings. Through the removal of unnecessary conservatism, it is expected that these modifications will make the seismic rehabilitation of Concrete Buildings more cost effective. Introduction: As described in the accompanying paper (Elwood 2009), ACI Committee on Seismic Repair and Rehabilitation (ACI 369) has undertaken the development of a Guide for Seismic Rehabilitation of Concrete Buildings based on the Concrete provisions of ASCE/SEI 41 Supplement 1 (2007). The first edition of the Guide will focus on cast- in-place moment-frame construction and the technical content will be very similar to ASCE/SEI 41 Supplement 1 with clarifications to improve applicability. Future editions of the Guide will include enhancements of many important topics including provisions for material testing, general assessment and modeling of components, beams, columns, joints and jacketed columns. In an effort to inform and engage the engineering community, this paper provides a brief summary of some of the changes expected in future editions of the Guide. It should be noted that these changes are in the early stages of development; hence, the eventual focus and approach for the changes may be modified prior to implementation in the Guide. Materials and Condition Assessment: Chapter 2 of the ACI 369 Guide for Seismic Rehabilitation of Existing Concrete Buildings provides methods for visual and comprehensive condition assessment of existing Concrete and steel materials and structural components. Data collection and testing procedures to quantify the existing material properties are presented. These provisions have seen only modest updating since the initial development of FEMA 273 in the mid 1990's and have often been criticized for being too arduous for most projects. The "comprehensive" testing level has requirements that may be considered
Jordi Corominas - One of the best experts on this subject based on the ideXlab platform.
-
Vulnerability of simple reinforced Concrete Buildings to damage by rockfalls
Landslides, 2010Co-Authors: Olga Mavrouli, Jordi CorominasAbstract:A procedure is presented for investigating the response of reinforced Concrete Buildings to rockfall impact. The method considers a single rock hit on the basement columns, and it includes four steps: (a) calculation of the probability of a rock impact on a member of the load-bearing system, taking into account the block size and the design of the structure; (b) evaluation of the response of one or more structural elements to the hit based on element capacity; (c) in the case of structural element failure, assessment of the robustness of the whole structural system, calculating the potential for progressive collapse; and (d) calculation of a damage index (DI), which is the ratio of structural elements that fail to the total number of structural elements. The proposed method is applied to a reinforced Concrete building for a range of rockfall paths and intensities. The analysis has been carried out for a 2-m-diameter block and velocities
-
Vulnerability of simple reinforced Concrete Buildings to damage by rockfalls
Landslides, 2010Co-Authors: Olga Mavrouli, Jordi CorominasAbstract:A procedure is presented for investigating the response of reinforced Concrete Buildings to rockfall impact. The method considers a single rock hit on the basement columns, and it includes four steps: (a) calculation of the probability of a rock impact on a member of the load-bearing system, taking into account the block size and the design of the structure; (b) evaluation of the response of one or more structural elements to the hit based on element capacity; (c) in the case of structural element failure, assessment of the robustness of the whole structural system, calculating the potential for progressive collapse; and (d) calculation of a damage index (DI), which is the ratio of structural elements that fail to the total number of structural elements. The proposed method is applied to a reinforced Concrete building for a range of rockfall paths and intensities. The analysis has been carried out for a 2-m-diameter block and velocities < 3.5 m/s. The possible damage range is found to be highly variable, with DI values ranging from 0.01 to 1 depending on the impact location and block velocity.
Olga Mavrouli - One of the best experts on this subject based on the ideXlab platform.
-
Vulnerability of simple reinforced Concrete Buildings to damage by rockfalls
Landslides, 2010Co-Authors: Olga Mavrouli, Jordi CorominasAbstract:A procedure is presented for investigating the response of reinforced Concrete Buildings to rockfall impact. The method considers a single rock hit on the basement columns, and it includes four steps: (a) calculation of the probability of a rock impact on a member of the load-bearing system, taking into account the block size and the design of the structure; (b) evaluation of the response of one or more structural elements to the hit based on element capacity; (c) in the case of structural element failure, assessment of the robustness of the whole structural system, calculating the potential for progressive collapse; and (d) calculation of a damage index (DI), which is the ratio of structural elements that fail to the total number of structural elements. The proposed method is applied to a reinforced Concrete building for a range of rockfall paths and intensities. The analysis has been carried out for a 2-m-diameter block and velocities
-
Vulnerability of simple reinforced Concrete Buildings to damage by rockfalls
Landslides, 2010Co-Authors: Olga Mavrouli, Jordi CorominasAbstract:A procedure is presented for investigating the response of reinforced Concrete Buildings to rockfall impact. The method considers a single rock hit on the basement columns, and it includes four steps: (a) calculation of the probability of a rock impact on a member of the load-bearing system, taking into account the block size and the design of the structure; (b) evaluation of the response of one or more structural elements to the hit based on element capacity; (c) in the case of structural element failure, assessment of the robustness of the whole structural system, calculating the potential for progressive collapse; and (d) calculation of a damage index (DI), which is the ratio of structural elements that fail to the total number of structural elements. The proposed method is applied to a reinforced Concrete building for a range of rockfall paths and intensities. The analysis has been carried out for a 2-m-diameter block and velocities < 3.5 m/s. The possible damage range is found to be highly variable, with DI values ranging from 0.01 to 1 depending on the impact location and block velocity.
Pierino Lestuzzi - One of the best experts on this subject based on the ideXlab platform.
-
damage prediction for regular reinforced Concrete Buildings using the decision tree algorithm
Computers & Structures, 2014Co-Authors: Amin Karbassi, Benyamin Mohebi, S Rezaee, Pierino LestuzziAbstract:To overcome the problem of outlier data in the regression analysis for numerical-based damage spectra, the C4.5 decision tree learning algorithm is used to predict damage in reinforced Concrete Buildings in future earthquake scenarios. Reinforced Concrete Buildings are modelled as single-degree-of-freedom systems and various time-history nonlinear analyses are performed to create a dataset of damage indices. Subsequently, two decision trees are trained using the qualitative interpretations of those indices. The first decision tree determines whether damage occurs in an RC building. Consequently, the second decision tree predicts the severity of damage as repairable, beyond repair, or collapse.
-
an equivalent frame model for seismic analysis of masonry and reinforced Concrete Buildings
Construction and Building Materials, 2009Co-Authors: Y Belmouden, Pierino LestuzziAbstract:Abstract In this paper a novel equivalent planar-frame model with openings is presented. The model deals with seismic analysis using the Pushover method for masonry and reinforced Concrete Buildings. Each wall with opening can be decomposed into parallel structural walls made of an assemblage of piers and a portion of spandrels. As formulated, the structural model undergoes inelastic flexural as well as inelastic shear deformations. The mathematical model is based on the smeared cracks and distributed plasticity approach. Both zero moment location shifting in piers and spandrels can be evaluated. The constitutive laws are modeled as bilinear curves in flexure and in shear. A biaxial interaction rule for both axial force–bending moment and axial force–shear force are considered. The model can support any shape of failure criteria. An event-to-event strategy is used to solve the nonlinear problem. Two applications are used to show the ability of the model to study both reinforced Concrete and unreinforced masonry structures. Relevant findings are compared to analytical results from experimental, simplified models and finite element models such as Drain3DX and ETABS finite element package.
Helen M. Goldsworthy - One of the best experts on this subject based on the ideXlab platform.
-
Seismic Fragility Assessment of Non-ductile Reinforced Concrete Buildings in Australia
Journal of Earthquake Engineering, 2020Co-Authors: Anita Amirsardari, Pathmanathan Rajeev, Elisa Lumantarna, Helen M. GoldsworthyAbstract:This study aims to assess the seismic performance of typical reinforced Concrete Buildings constructed in Australia before the enforcement for seismic design. The response of both the primary later...
-
Suitable intensity measure for probabilistic seismic risk assessment of non-ductile Australian reinforced Concrete Buildings
Bulletin of Earthquake Engineering, 2019Co-Authors: Anita Amirsardari, Pathmanathan Rajeev, Elisa Lumantarna, Helen M. GoldsworthyAbstract:This study investigates the suitability of various intensity measures for conducting probabilistic seismic risk assessment of low- to mid-rise non-ductile reinforced Concrete Buildings with various plan configurations located in low-to-moderate seismic regions. Probabilistic seismic demand models are developed by conducting three-dimensional nonlinear time history analyses. The building response is defined to be dependent on component response and interstorey drift limits. In total the suitability of eleven intensity measures is evaluated by examining five criteria: efficiency, practicality, proficiency, sufficiency, and hazard computability. Based on the first four criteria it is identified that peak ground velocity, peak ground displacement, and maximum spectral displacement response are the most suitable intensity measures. Hazard computability is then utilised to select the optimum intensity measure for a hazard model in accordance with the Australian standards.
-
Fragility Curves for Limited Ductile Reinforced Concrete Buildings
2018Co-Authors: Elisa Lumantarna, Nelson Lam, Hing-ho Tsang, John W Wilson, Emad Gad, Helen M. GoldsworthyAbstract:Reinforced Concrete Buildings make up the majority of Australian building stocks. Structural elements of these Buildings are often designed with limited to nonductile detailing. With a very low building replacement rate many of the Australian Buildings are vulnerable to major earthquakes and pose significant risk to lives, properties and economic activities. This paper presents studies on seismic vulnerability assessments of limited ductile reinforced Concrete Buildings. Fragility curves have been developed for three types of Buildings, Buildings that are mainly supported by shear or core walls, Buildings that are supported by shear walls and moment resisting frames and podium-tower Buildings featuring a transfer structure. The studies form a part of a collaborative research under the Bushfire and Natural Hazards Cooperative Research Centre (BNHCRC) on “cost-effective mitigation strategy development for building related earthquake risk”.