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The large-scale and catastrophic impacts of Hurricanes Katrina and Rita in 2005 challenged the efficacy of traditional postdisaster temporary housing methods. To address these challenges, the U.S. Congress appropriated $400 million to the Department of Homeland Security to support alternative housing pilot programs, which encourage innovative housing solutions that will facilitate sustainable and permanent affordable housing in addition to serving as temporary housing. Facilitating and maximizing the sustainability of postdisaster alternative housing is an important objective that has significant social, economic, and environmental impacts. This paper presents the development of a novel optimization model that is capable of (1) evaluating the sustainability of integrated housing recovery efforts under the alternative housing pilot program and (2) identifying the housing projects that maximize sustainability. An application example is analyzed to demonstrate the use of the developed model and its unique capabilities in maximizing the sustainability of integrated housing recovery efforts after natural disasters. DOI: 10.1061/(ASCE)CO. 1943-7862.0000185 CE Database subject headings: Optimization; Housing; Hurricanes; Disaster recovery; United States. Author keywords: Optimization; Postdisaster alternative housing; Sustainability; Housing Recovery.

Due to the nonlinear nature of coordinate transformations, evaluation and calibration of multiaxial loading systems in global Cartesian coordinates are challenging problems. This study proposes a systematic calibration method for multiaxial loading systems in global coordinates using an external measurement system. Global coordinate measurement for a multiaxial loading system is usually obtained from a geometric transformation based on internal actuator measurements. However, any misrepresentation of initial actuator configuration (e.g., origin, pin locations, etc.) introduces errors and cross-talk in the global Cartesian coordinates. Such errors and cross-talk cannot be observed or eliminated based on internal measurements. The method proposed in this paper is based on the sensitivity of the global coordinates with respect to the initial actuator length. To validate the proposed method, calibration is performed using the state-of-the-art Load and Boundary Condition Box at University of Illinois at Urbana-Champaign as the multiaxial loading system and the Krypton Dynamic Measurement Machine as the external measurement system. Experimental results demonstrate that the proposed sensitivity-based external calibration method is effective for improving control accuracy and reducing cross-talk of multiaxial loading systems in global Cartesian coordinates. DOI: 10.1061/(ASCE)0733-9399(2010)136:2(189) CE Database subject headings: Sensitivity analysis; Calibration; Transformation.

A multiplatform simulation of a highway overcrossing bridge is introduced where the embankments, abutments, and pile groups are modeled in a powerful finite-element (FE) package with nonlinear soil material model while the bridge is modeled in another FE package that excels in fiber-based frame analysis. The Meloland Road Overcrossing Bridge, which is heavily instrumented, is selected as a reference analysis model due to the existence of measured data. The components as well as the integrated system are verified through comparison with previous studies and measured data. The stiffness of abutments and pile foundations are evaluated by three-dimensional finite-element analysis and compared with those from previous investigations. The analytical models of abutments and foundations are combined with the structural model using the multiplatform analysis framework, UI-SimCor. The dynamic properties of the model for multiplatform analysis are compared with those evaluated from system identification techniques using recorded ground motion. Finally, response history analyses are conducted with recorded free-field ground motion. The analysis results are in very good agreement with measured response showing the promising potential of multiplatform dynamic simulation. DOI: 10.1061/(ASCE)0733-9445(2008)134:4(651) CE Database subject headings: Seismic analysis; Roads; Simulation; Computer software; Bridges, highway.

Motivated by the observation that existing damage indices do not take into account the bidirectional and torsional response effects, a new three dimensional damage index is proposed in this paper. The derivation is based on decomposing the 3D structure into planar frames. A local damage index that is sensitive to out-of-plane responses is described and a method to combine local damage indices is presented. The proposed index is verified by comparison with conventional damage indices. DOI: 10.1061/(ASCE)0733-9445(2006) 132:9(1482) CE Database subject headings: Damage assessment; Earthquake engineering; Biaxial loads; Torsion.

Recent analytical studies have shown that reduced column compression and even tension may be experienced by intermediate stories of medium to high-rise reinforced concrete (RC) structures. This is a consequence of high overturning moments coexisting with vertical ground motion. In recognition of such observations, the present study was initiated to investigate the seismic performance of interior beam-column subassemblages under reduced column compression or net tension. A state-of-the-art synchronized shake-table facility was used to test a total of six ordinary and marginal high-strength RC interior subassemblages. A nonconventional design approach was adopted to ensure pure panel-zone (PZ) shear failure, hence a realistic estimate of joint shear strength will ensue. Results indicated loss of shear capacity and increase in deformability when compression column load is markedly reduced or tension is experienced. Findings of this investigation are most useful in providing necessary information about the effect of axial tension on the PZ shear capacity, the joint confinement efficiency, and the overall structural stability in areas of potential high vertical earthquake excitations.

In this paper, modeling approaches describing the hysteretic behavior of reinforced-concrete columns subjected to cyclic deformation reversals are investigated. The inelastic flexure and shear response of a reinforced-concrete column subjected to cyclic deformation is evaluated utilizing lumped hysteretic representations that exhibit efficiency and ease of modeling. The analytical predictions obtained with the new formulations are compared with experimental results from the literature. Comparisons between results with and without shear interaction reveal the importance of the flexure-shear interrelationship and the adequacy of the proposed approach in terms of strength and stiffness predictions.

Analytical methods are frequently utilized for structural assessment due to their simplicity and cost-effectiveness. However, modeling of material inelasticity and geometric nonlinearity under reversed inelastic deformations is still very challenging and its accuracy is difficult to quantify. On the other hand, realistic experimental assessment is costly, time-consuming, and impractical for large or spatially extended structures. Hybrid simulation has been developed as an approach that combines the realism of experimental techniques with the economy of analytical tools. In hybrid simulation, the structural is divided into several modules such that the critical components are tested in the laboratory, while the rest of the structure is simulated numerically. The equations of motion solved in the computer enable the integration of the analytical and experimental components at each time increment. The objective of this article is to apply a newly developed identification and model updating scheme to acquire the material constitutive relationship from the physically tested specimen during the analysis to two complex hybrid simulation case studies. The identification scheme is developed and verified in a companion article, while the two experiments presented in this article are selected such that they address different structural engineering applications. First, a beam-column steel connection with heat treated beam section is analyzed. Afterwards, the response of a multi-bay concrete bridge is investigated. The results of these two examples demonstrate the effectiveness of model updating to improve the numerical model response as compared to the conventional hybrid simulation approaches. [ABSTRACT FROM PUBLISHER]

Hybrid simulation has been effectively utilized to assess structural response subjected to intense dynamic loads. The process comprises dividing the structure into experimental and numerical modules. The experimental modules represent the critical components responses, which cannot be idealized reliably through analytical approaches. The responses of the different modules are combined through a stepwise integration scheme. In conventional hybrid simulations, the number of experimental components is restricted by the capacity of the test facility; usually 1–3 components, and the numerical simulation does not benefit from the information acquired from the tested component during the analysis. In this article, a framework is proposed to identify the material constitutive relationship from the tested component(s) and to update the corresponding numerical parts that share close characteristics with the physical tests. Optimization tools and neural networks are presented as alternatives for the identification procedure; the framework is however extendable and scalable. The communication protocol between the different structural components is also discussed within the proposed framework. Several analytical examples are presented to prove the feasibility of the presented framework, while experiments are used to verify the process in a companion article. [ABSTRACT FROM PUBLISHER]

Field investigations after the recent Tohoku and Christchurch earthquakes reported failure of structural systems due to multiple earthquakes. In most failure cases the reported damage was mainly due to dramatic loss of stiffness and strength of structural elements as a result of material deterioration due to repeated earthquake loading. This study aims to investigate the degrading behavior of reinforced concrete frame systems subjected to Tohoku and Christchurch earthquake sequences. Numerical models of RC frames that incorporate damage features are established and inelastic response history analyses are conducted. The results presented in this study indicate that multiple earthquake effects are significant. [ABSTRACT FROM AUTHOR]

SUMMARY Civil engineering structures are often subjected to multidirectional actions such as earthquake ground motion, which lead to complex structural responses. The contributions from the latter multidirectional actions to the response are highly coupled, leading to a MIMO system identification problem. Compared with single-input, multiple-output (SIMO) system identification, MIMO problems are more computationally complex and error prone. In this paper, a new system identification strategy is proposed for civil engineering structures with multiple inputs that induce strong coupling in the response. The proposed solution comprises converting the MIMO problem into separate SIMO problems, decoupling the outputs by extracting the contribution from the respective input signals to the outputs. To this end, a QR factorization-based decoupling method is employed, and its performance is examined. Three factors, which affect the accuracy of the decoupling result, including memory length, input correlation, and system damping, are investigated. Additionally, a system identification method that combines the autoregressive model with exogenous input (ARX) and the Eigensystem Realization Algorithm (ERA) is proposed. The associated extended modal amplitude coherence and modal phase collinearity are used to delineate the structural and noise modes in the fitted ARX model. The efficacy of the ARX-ERA method is then demonstrated through identification of the modal properties of a highway overcrossing bridge. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Hybrid simulation has emerged as a relatively accurate and efficient tool for the evaluation of structural response under earthquake loading. In conventional hybrid simulation the response of a few critical components is obtained by testing while the numerical module is assumed to follow an analytical idealization. Where there is a much larger number of analytical components compared to the experimental parts, the overall response may be dominated by the idealized parts hence the value of hybrid simulation is diminished. It is proposed to modify the material constitutive relationship of the numerical model during the test, based on the data obtained from the physically tested component. An approach based on genetic algorithms is utilized as an optimization tool to identify the constitutive relationship parameters used in updating the numerical model. The proposed model updating approach is verified through two analytical examples of steel and reinforced concrete frames. The results show the effectiveness of the updating process in minimizing the errors, compared to the assumed exact solution. [ABSTRACT FROM PUBLISHER]

The behavior of semirigid partial-strength connections has been investigated through either experimental component testing or detailed three-dimensional (3D) finite-element (FE) models of beam-column subassemblies. Previous experiments on semirigid partial-strength connections were conducted under idealized loads and boundary conditions, which do not represent real situations. In addition, the developed 3D FE models are computationally expensive and have primarily been used under monotonic loadings. Evaluating the full potential of any connection requires a system-level investigation, whereby the effect of the local behavior of the connection on the global response of the structural system is considered. Moreover, the connection should be tested under realistic load and boundary conditions and/or analyzed using an accurate yet computationally affordable analytical model. This paper represents a new system-level hybrid simulation application aimed at investigating the seismic performance of semirigid partial-strength steel frames with top and seat angles with double web-angle connections. The analytical component of the simulation comprises a detailed two-dimensional nonlinear FE model. The experimental component of the simulation consists of a full-scale beam-column subassembly with loading and boundary conditions that are in full interaction with the rest of the frame. The paper provides an overview of the hybrid simulation application and highlights the major results. The simulations were conducted at the Multi-Axial Full-Scale Sub-Structured Testing and Simulation Facility at the University of Illinois, which is part of the National Science Foundation Network for Earthquake Engineering Simulation. [ABSTRACT FROM AUTHOR]

The accuracy of fragility functions is critical for regional risk and loss estimations. This paper proposes a two-stage approach to generate improved fragility functions for engineering structures using field measurement and experimental data. In the first stage, the linear and nonlinear parameters of the bridge model are calibrated using measured earthquake responses and cyclic testing data; analytical fragilities are then generated with the calibrated model. In the second stage, a Bayesian updating approach is used to further update the derived fragilities using hybrid (analytical-experimental) simulation results. To illustrate the effectiveness of the proposed approach, fragility functions are generated for the Meloland Road Overcrossing Bridge considering four cases that represent an increasing level of data availability. A comparison of the four sets of fragility functions shows that appropriate calibration of bridge model is critical to the accuracy of the fragilities. In addition, hybrid simulation provides an economic and efficient way of validating and improving the accuracy of fragility functions through Bayesian updating. [ABSTRACT FROM AUTHOR]

The objective of the research presented in this paper is to investigate, experimentally, the effect of material- and section-level parameters on the structural response of concrete and engineered cementitious composite (ECC) buildings. In addition to testing of columns under monotonic, cyclic, and static-time history loading, hybrid simulation of structural frames is conducted. Stiffness, strength, ductility, and energy absorption capacity are selected as the response measures that represent the behavior of structures under seismic actions. The investigated variables are reinforcement ratios, ECC material properties, and axial load levels. The results are proposed as basic guidelines to determine the performance enhancement in terms of stiffness, strength, ductility, and energy absorption capacity, which could be achieved by replacing concrete with the high-performance material ECC. [ABSTRACT FROM AUTHOR]

Unreinforced masonry (URM) structures represent a significant portion of the residential building stock of the central and eastern United States. Fifteen percent of homes in the eight-state region impacted by the New Madrid Seismic Zone are URM buildings. The brittle nature of URM buildings further supports a thorough consideration of seismic response given the susceptibility to severe failure modes. Currently, there is a pressing need for analytically based fragility curves for URM buildings. To improve the estimation of damage-state probabilities through the development of simulation-based URM fragilities, an extensive literature survey is conducted on pushover analysis. Using these data, capacity curves are generated, from which damage performance limit states are defined. Demand is simulated using synthetically derived accelerograms representative of the central and eastern United States. Structural response is evaluated using an advanced capacity spectrum method. Capacity, demand, and response are thus derived analytically and utilized to generate a more reliable and uniform set of fragility curves for use in loss-assessment software. This paper presents a framework amenable to rapid, flexible updating that, with the appropriate database of studies, is capable of producing curves representative of any URM building typology subjected to a specified hazard. The curves are expressed in multiple forms to demonstrate capability of use in various loss-assessment applications. [ABSTRACT FROM AUTHOR]

It is desirable to use probabilistic performance targets for decision-making as it relates to intervention methods, because of high uncertainties of structure responses under earthquake loadings. This is based on the probabilistic performance assessment of structures with various retrofit options. Extensive computer simulations to account for the randomness in both input motion and response characteristics have been a serious obstacle to the adoption of the probabilistic performance assessment in the decision of seismic intervention schemes. This study presents an approach whereby a fragility assessment result with known reliability is derived based on the fundamental response quantities of stiffness, strength and ductility. An exact solution for a generalised single-degree-of-freedom system is employed to construct a response database of maximum responses. Once the fundamental response quantities of a wide range of structural systems are defined, the fragility assessment for various limit states can be constructed without recourse to further simulation. By virtue of its instantaneous nature, the proposed method is especially useful for practical application of the analytical fragility assessment that includes the planning of seismic rehabilitation and regional earthquake mitigation, where fast estimation of probabilities of reaching damage states for a large number of structural configurations and different mitigation measures is required. For cases of selection between different retrofitting options, the proposed approach gives rapid estimates of probabilities of various damage levels inflicted on the structures under consideration, given only the stiffness, strength and ductility for each alternative retrofitting scheme. The presented fragility contour and constant fragility spectra enable the engineer to use visualised data sets to practically and conveniently investigate the probabilistic performance of every retrofit option. [ABSTRACT FROM AUTHOR]

Transportation networks are critical civil infrastructures susceptible to natural hazards such as earthquakes. It is essential to understand and model the travel demand in emergency situation when considering measures to secure traffic function immediately after the earthquake and to restore the performance of transportation networks. Post-earthquake travel demand is complicated, and the changes of traffic pattern after the event are often coupled with the physical damage of transportation infrastructures. This study develops a scenario-based methodology to model the performance of post-earthquake transportation systems by extending the combined trip distribution and assignment model. Several general assumptions are made on post-earthquake travel behaviour and emergency traffic management measures. The proposed methodology is demonstrated with the Sioux-Falls road network and results are presented. The findings suggest that such scenario-based integrated methodology can capture the post-earthquake travel characteristics and is capable to provide more reasonable results than conventional transportation modelling approaches. The methodology can be used to model the emergency demand and post-earthquake performance of transportation systems. It is helpful to aid traffic planners and emergency managers in evaluating their contingency traffic plans and making decisions in emergency management. [ABSTRACT FROM AUTHOR]

The bridge network, as part of the critical civil infrastructure, is susceptible to natural and man-made hazards. It is essential that the network retains its traffic-carrying capacity after a disastrous earthquake to ensure efficient evacuation of at-risk population to safe zones and timely dispatch of emergency response resources to the impacted area. Because of limited resources, it is important to prioritize bridge retrofit projects and manage disaster mitigation resources under a strategic budget plan. This paper proposes a methodology to find the optimal bridge retrofit program that aims to maximize the postdisaster network evacuation capacity. The uncertainties of earthquake intensity, bridge structural damage, and bridge traffic-carrying capacities are addressed by using a Monte Carlo simulation framework with established bridge fragility curves and damage-functionality relationships, and the effectiveness of preserving evacuation capacity is calculated on the basis of a network design model. The proposed methodological framework is demonstrated with the transportation network in Memphis, Tennessee, and numerical experiments show that the proposed framework solves the problem efficiently. The modeling framework can help transportation agencies maximize the effectiveness of investment. Emergency managers can also use the model to enhance preparedness and emergency response efficiency, which in turn improves the infrastructure systems' resilience against extreme events. [ABSTRACT FROM AUTHOR]

The seismic performance of low-rise frames with energy dissipative semirigid connections is evaluated under far and near field artificial ground motion records. Four different connection capacities are employed in the frames and are characterized by two different moment-hardening ratios and two different hysteresis models. Nonlinear time-history and Fourier analyses are utilized to assess the seismic performance of 24 semirigid and 2 rigid frames. In the nonlinear time-history analyses, nine far field and nine near field artificial ground motion records generated from three different attenuation relations are used. Finally, the seismic performance of the rigid frames and the semirigid frames are compared, and the conditions under which the semirigid frames show better seismic performance than rigid frames are investigated. The results show that 25 of 26 sample frames satisfy all acceptance criteria and exhibit reliable seismic performance. [ABSTRACT FROM AUTHOR]

This paper presents analytical assessment of the effect of vertical earthquake ground motion on RC bridge piers. A bridge structure damaged during the Northridge Earthquake and a Federal Highway concept bridge design are examined. The effects of a suite of earthquake ground motion records with different vertical-to-horizontal peak acceleration ratios on the two bridges are presented and the results are compared with the case of horizontal-only excitation. The effects of arrival time interval between horizontal and vertical acceleration peaks are also reported and compared to the case of coincident motion. It is observed that the inclusion of the vertical component of ground motion has an important effect on the response at all levels and components. It is therefore concluded that vertical motion should be included in analysis for assessment and design, especially that there are no particular challenges impeding its inclusion. [ABSTRACT FROM AUTHOR]

Abstract: Earthquake loss estimation procedures exhibit aleatory and epistemic uncertainty imbedded in their various components; i.e. seismic hazard, structural fragility, and inventory data. Since these uncertainties significantly affect decision-making, they have to be considered in loss estimation to inform decision- and policymakers and to ensure a balanced view of the various threats to which society may be subjected. This paper reviews the uncertainties that affect earthquake loss estimation and proposes a simple framework for probabilistic uncertainty assessment suitable for use after obtaining impact results from existing software, such as HAZUS-MH. To avoid the extensive calculations required for Monte Carlo simulation-based approaches, this study develops an approximate method for uncertainty propagation based on modifying the quantile arithmetic methodology, which allows for acceptable uncertainty estimates with limited computational effort. A verification example shows that the results by the approximation approach are in good agreement with the equivalent Monte Carlo simulation outcome. Finally, the paper demonstrates the proposed procedure for probabilistic loss assessment through a comparison with HAZUS-MH results. It is confirmed that the proposed procedure consistently gives reasonable estimates. [Copyright &y& Elsevier]

This article presents a novel approach for deriving Retrofit Design Spectra (RDS) that are intended for use in preliminary development and assessment of seismic upgrading scenarios of existing structures. The new spectral representation relates the characteristics of the intervention method chosen as the core of the upgrading strategy, with the ductility and strength demand of the retrofitted structure. The methodology utilized for the derivation of the RDS is based on the Capacity Spectrum Method where the capacity curve is described by relationships for global and local intervention methods that are parameterized in terms of fundamental response quantities. The proposed spectra provide direct insight into the complex interrelation between the characteristics of the intervention method and the implications of the upgrading scenario on demand. Alternative retrofit solutions are thus assessed in an efficient way. A case study is used to illustrate practical application of the new approach. [ABSTRACT FROM AUTHOR]

Seismic fragility relationships, including the soil-structure interaction (SSI) of a common bridge configuration in central and eastern USA, are derived in this study. Four different modelling methods are adopted to represent abutments and foundations of the bridge, namely, (a) fixed abutments and foundations, (b) lumped springs developed from conventional pile analysis of piles at abutments and foundations, (c) lumped springs developed from three-dimensional finite element (3D FE) analysis of abutments and foundations and (d) 3D FE models. Seismic demand on the bridge components is estimated from inelastic response history analysis of the SSI systems. Finally, fragility curves of the components and bridge system are derived. The four different SSI approaches result in different seismic fragility. The implication of this work is that careful consideration is necessary when selecting an analytical representation of a soil and foundation system to obtain reliable earthquake impact assessment. In addition, it is found that abutment bearings are the most critical components for the studied bridge configuration. [ABSTRACT FROM AUTHOR]

A complete methodology is presented for the seismic fragility assessment of reinforced concrete high-rise buildings. The key steps of the methodology are illustrated through an example of the fragility assessment of an existing 54-story building with a dual core wall system. The set of rigorously derived probabilistic fragilities are the first published for high-rise reinforced concrete buildings. The inelastic nonlinear dynamic analyses for the fragility assessments are made using a simplified lumped-parameter model that was derived from highly detailed FE models using genetic algorithms. New definitions for performance limit states were based on the results of detailed pushover analyses of a distributed inelastic nonlinear finite element model that includes shear-flexure-axial interaction effects. To develop the fragility relationships, 1800 dynamic response history analyses were conducted. This study considered uncertainty in structural material values as well as in seismic demand. Thirty strong motion records were selected for use in the analyses that would produce an appropriate range in structural response characteristics due to variation in magnitude, distance and site condition. The overall approach is generic and can be applied to developing computationally efficient and probabilistically-based seismic fragility relationships for reinforced concrete high-rise buildings of different configurations. [ABSTRACT FROM AUTHOR]

This paper presents a design-variable-based inelastic hysteretic model for beam-column connections. It has been well known that the load-carrying capacity of connections heavily depends on the types and design variables even in the same connection type. Although many hysteretic connection models have been proposed, most of them are dependent on the specific connection type with presumed failure mechanisms. The proposed model can be responsive to variations both in design choices and in loading conditions. The proposed model consists of two modules: physical-principle-based module and neural network (NN)-based module in which information flow from design space to response space is formulated in one complete model. Moreover, owing to robust learning capability of a new NN-based module, the model can also learn complex dynamic evolutions in response space under earthquake loading conditions, such as yielding, post-buckling and tearing, etc. Performance of the proposed model has been demonstrated with synthetic and experimental data of two connection types: extended-end-plate and top- and seat-angle with double-web-angle connection. Furthermore, the design-variable-based model can be customized to any structural component beyond the application to beam-column connections. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Nonuniform seismic excitation has been shown through previous analytical studies to adversely affect the response of long-span bridge structures. To further understand this phenomenon, this study investigates the response of complex straight and curved long-span bridges under the effect of parametrically varying asynchronous motion. The generation process and modeling procedures are presented in a companion paper. A wide-ranging parametric study is performed aimed at isolating the effect of both bridge curvature and the two main sources of asynchronous strong motion: geometric incoherence and the wave-passage effect. Results from this study indicate that response for the 344 m study structure is amplified significantly by nonsynchronous excitation, with displacement amplification factors between 1.6 and 3.4 for all levels of incoherence. This amplification was not constant or easily predicable, demonstrating the importance of inelastic dynamic analysis using asynchronous motion for assessment and design of this class of structure. Additionally, deck stiffness is shown to significantly affect response amplification, through response comparison between the curved and an equivalent straight bridge. Study results are used to suggest an appropriate domain for consideration of asynchronous excitation, as well as an efficient methodology for analysis. [ABSTRACT FROM AUTHOR]

Based on observed damage patterns from previous earthquakes and a rich history of analytical studies, asynchronous input motion has been identified as a major source of unfavorable response for long-span structures, such as bridges. This study is aimed at quantifying the effect of geometric incoherence and wave arrival delay on complex straight and curved bridges using state-of-the-art methodologies and tools. Using fully parametrized computer codes combining expert geotechnical and earthquake structural engineering knowledge, suites of asynchronous accelerograms are produced for use in inelastic dynamic analysis of the bridge model. Two multi-degree-of-freedom analytical models are analyzed using 2,000 unique synthetic accelerograms with results showing significant response amplification due to asynchronous input motion, demonstrating the importance of considering asynchronous seismic input in complex, irregular bridge design. The paper, Part 1 of a two-paper investigation, presents the development of the input motion sets and the modeling and analysis approach employed, concluding with sample results. Detailed results and implications on seismic assessment are presented in the companion paper: Effect of Asynchronous Motion on Complex Bridges. Part II: Results and Implications on Assessment. [ABSTRACT FROM AUTHOR]

A new generation of tools is needed to allow researchers and practicing engineers the ability to leverage investments in new methodologies and software infrastructure while enabling customization to local conditions. MAEviz represents such a next generation of seismic risk assessment software, based on the Mid-America Earthquake (MAE) Center research in Consequence-based Risk Management (CRM) and is designed to be extended, customized, and evolved to meet the needs of specific organizations and regions. MAEviz helps bridge the gap between researchers, practitioners, and policy-makers by integrating the latest research findings and most accurate data, using state-of-the-art methodologies, in an extensible software platform. [ABSTRACT FROM AUTHOR]

In the absence of comprehensive and statistically viable observational damage data, there is a pressing need for simulation-based fragility relationships for populations of structures so as to improve the reliability of earthquake loss assessment studies. In this article, improved fragility relationships for woodframe structures are developed based on inelastic response. Capacity curves are obtained from detailed finite element models, demand is simulated by synthetically generated earthquake ground motions representing a probable earthquake in the Central USA, and structural assessment is carried out using an advanced capacity spectrum method (CSM) presented elsewhere. Thus, all the required components of fragility analysis—namely, capacity, demand, and structural response—are founded on simulated (analytical) behavior. Building classification of the HAZUS loss assessment software is adopted and both HAZUS-compatible and conventional fragility relationships are derived for two different soil conditions. Comparisons with HAZUS fragility curves are given. The parameters of the improved fragility relationships are provided for reliable use in loss assessment software. [ABSTRACT FROM AUTHOR]