A new law known as the "Urban Renewal Law" for risk mitigation was passed in May 2012 with the objective of reducing seismic risk associated with the existing building stock in Turkey. As stated in the law, new provisions are set forth to assess and to identify seismically vulnerable residential buildings as quickly as possible. The buildings that are classified as high risk are either demolished or strengthened. New buildings are constructed through the financing options provided by the government. In this study, first, the technical provisions of seismic risk assessment, based on linear elastic analysis, are briefly described with special emphasis on the deformation limits. Because of the inability of the linear elastic analysis to allow for redistribution, some flexibility is provided on how many vertical load bearing elements are allowed to exceed their performance limits. Afterwards, three case study buildings are analyzed by using the new provisions and ASCE/SEI 41-06 linear elastic procedure. Level and sources of conservatism in the two approaches are critically evaluated.

There are many vulnerable reinforced concrete (RC) buildings located in earthquake-prone areas around the world. These buildings are characterized by the lack of seismic details and corresponding non-ductile behavior and significant potential of partial and global collapse. One of the current challenges of the earthquake engineering profession and research communities is the identification of such buildings and determination of effective and economical retrofit methods for response enhancement. Identification of these buildings is not a trivial task due to the various sources of non-ductile behavior and the large number of involved sources of uncertainty. Furthermore, accurate determination of collapse-prone buildings is important from an economical perspective. Unfortunately, there are not enough economical resources to retrofit all the non-ductile buildings that have the symptoms for collapse potential. In order to use the available monetary resources in an effective manner, these buildings should be accurately and reliably ranked to identify those that are most vulnerable to collapse. This paper intends to provide a contribution to the accurate determination of the most collapse vulnerable non-ductile RC buildings by discussing the methods from existing literature and exploring the research needs related to (a) gravity load failure modeling and (b) consideration of sources of uncertainty in an efficient manner.

Over the past few decades, flat plate concrete building systems have been widely adopted in the United States and other countries because it enables not only to save construction time and cost but also to make better use of interior spaces. However, it has been observed that such buildings whose columns are cast into the concrete flat plate are highly vulnerable to collapse. Such integrated slab-column frames have suffered severe damage or completely collapsed during the past earthquake events. The main failure mode of these structures is punching shear. Although a general guideline for seismic design and a seismic rehabilitation design guideline for both existing and new reinforced concrete frame structures are specified in ACI 318 and ACI 369R, respectively, many uncertainties have still resided in the modeling parameters to accurately predict seismic behavior of the flat plate concrete frame structures. Therefore, a new chart of allowable plastic rotation values for correlating values of gravity shear ratio is presented in this study with the objective of updating the modeling parameters of ACI 369R. The major issues which lead to errors in evaluating flat plate concrete structural behavior under seismic loads are thoroughly investigated. Also, dominant parameters from previous and recent experiments on integrated slab-column connections subjected to seismic loading are utilized to assess the estimation of seismic performance of the flat plate system based on ACI 369R. Consequently, although it is confirmed that there is a trend in correlation between the allowable plastic rotation and gravity shear ratio while almost no correlation is observed with reinforcement ratio, more experimental data are necessary to enhance this correlation study. It is also noticed that the current ACI 369 recommendations for allowable plastic rotation values for slab-column connection under seismic and gravity loading are unconservative.

ASCE/SEI 41-06 provides guidelines for evaluating the seismic adequacy of existing buildings. For nonlinear dynamic analysis of a building, ASCE 41 provides modeling parameters to define the backbone curve for the response of structural components. Seismic adequacy is then determined by comparing simulated response to predetermined acceptance criteria. In the reinforced concrete (RC) community, there is interest in evaluating the modeling parameters and acceptance criteria for RC components, and if deemed necessary, developing updated values that reflect the current state of understanding of the seismic performance of RC components. For some structural components (e.g. columns), large databases of experimental data can be used to develop empirical acceptance criteria that reflect the behavior of the component. In the case of slender structural walls, relatively limited tests have been conducted such that sufficient variation in critical design and loading characteristics including shape, aspect ratio (elevation and cross-sectional), confinement, and axial load are not represented by experimental data to justify use of an experimental database to develop acceptance criteria. Evaluation of this limited set of experimental data indicates current ASCE 41 modeling parameters and acceptance criteria for flexure-controlled walls is inappropriate, generally resulting in overprediction of wall deformation capacity at high axial load ratios and underprediction at low axial load ratios and low shear demands. Although suitable for evaluation of criteria, the data set is not sufficiently varied such that revised provisions can be developed. To overcome the lack of sufficient experimental data, a parameter study was conducted to provide data to support development of updated acceptance criteria. The parameter study was conducted using a modeling approach validated to provide accurate simulation of flexural failures in slender reinforced concrete walls. Simulation results were used to develop preliminary recommendations for revised modeling parameters for slender RC walls. An evaluation of these simulation results and preliminary recommendations for revised flexure-controlled RC wall modeling parameters are presented in this paper.

The results of laboratory testing and earthquake reconnaissance studies of reinforced concrete frames indicate that beam‐column joint deformation can determine total frame deformation and that for older buildings joint failure can result in frames losing lateral and gravity load carrying capacity. Given the impact of joints on frame response, numerical models used to evaluate the earthquake performance of reinforced concrete frames must include nonlinear joint models. This paper reviews previously proposed models for simulating joint response with the objective of identifying models that provide i) accurate simulation of response to earthquake loading, ii) simple implementation in nonlinear analysis software, iii) numerical robustness, iv) computational efficiency, and v) objective calibration procedures. Ultimately, no set of models was identified that met all of these requirements for the range of geometric and design parameters found in reinforced concrete buildings in the United States. With the objective of extending current modeling capabilities for interior joints, an experimental data set was assembled. The data set was used to evaluate existing envelope response models and used to calibrate cyclic response parameters for use with the preferred existing model. A new response model for interior beam‐column joints is presented that meets the above requirements for the range of geometric and design parameters found in reinforced concrete buildings in the United States.