Fragility curves are functions which represent the probability that a given structure’s response ... more Fragility curves are functions which represent the probability that a given structure’s response to various seismic (conditions) excitations exceeds performance limit states. As such, fragility curves are a measure of performance in probabilistic terms. The major objectives of MCEER research on fragility information are: (1) developing efficient and accurate methods to calculate fragility curves for structural and nonstructural components and for global assemblies (systems); (2) establishing fragility information as a base for performance-based design, cost and loss assessment, and decision policies; (3) developing optimal strategies for seismic rehabilitation based on cost-benefit analysis; and (4) establishing rational performance limit states based on interaction between engineering and socioeconomic issues.
1 Assistant Professor, Department of Civil Engineering, Indian Institute of Technology, New Delhi... more 1 Assistant Professor, Department of Civil Engineering, Indian Institute of Technology, New Delhi, India 2 Professor, Department of Civil Engineering, State University of New York, Buffalo, NY 14260 3 Associate Professor, Department of Civil Engineering, State University of New York, Buffalo, NY 14260 In reinforced concrete masonry shear walls with ungrouted cells, the longitudinal steel reinforcing bars are not bonded (unbonded) to the neighboring masonry. As a result, the steel strains as well as forces are governed by the relative displacements of the end anchorages and are, therefore, dependent on the deformations of the entire wall. After the development of the first flexural crack at the base, the in-plane lateral load is resisted primarily by arch action (tie-strut mechanism) due to the absence of bonding in such walls, as opposed to beam action which is the dominant load resisting mechanism for shear walls with bonded reinforcement. Further, the flexural cracking causes a pa...
The importance of nonstructural components has been demonstrated during past seismic events since... more The importance of nonstructural components has been demonstrated during past seismic events since damage to such components can be not only a critical threat to life safety in extreme cases, but also result in a substantial reduction of functionality of buildings. Current standards do not explicitly provide guidance for the seismic design of a suspended ceiling system, one of important nonstructural components in buildings, due to their complex construction. In order to understand the dynamic behavior of a suspended ceiling system, full scale shake table tests of 20ft. × 50ft. and 20ft. × 20ft. ceiling systems were conducted at University at Buffalo. Identified failure modes that describe functionality of the system include (i) failure of perimeter connections, (ii) failure of grid component connections, (iii) fallen panels, and (iv) system collapse. Based on the observed failure mechanisms and the physical properties of a ceiling structure, several simplified uniaxial analytical mo...
The concept of Disaster Resilience has received considerable attention in recent years and it is ... more The concept of Disaster Resilience has received considerable attention in recent years and it is increasingly used as an approach for measuring response of communities to natural disasters. Recently a framework named PEOPLES has been developed by MCEER to measure performance of communities to natural disasters. The method includes seven dimensions that include both technical and socio-economic aspects. All resilience dimensions and their respective indices to measure community performances are obviously interdependent. As first step, the physical dimension has been implemented in software and indices have been proposed to measure performance of buildings and lifelines. This paper tries to focus on developing methodologies to consider interdependencies between buildings (e.g. hospitals, strategic buildings, etc) and lifelines (road networks, etc.). An approach considering network interdependencies have been developed which is based on the time series analysis of the restoration curve...
This paper presents preliminary results and analysis of a cantilever load test on two types hollo... more This paper presents preliminary results and analysis of a cantilever load test on two types hollow-core composite insulators and summarizes the response of the insulators to different types of loading. The tube of the insulator is a cylindrical shell of fibers-glass in a resin-based matrix with aluminum flange end fittings. The integrity of the tube-flange connection is checked for leaks, slip, damage, and bond degradation. Tests indicate that he actual cantilever load causing failure was much higher than the rated SML provided by the manufacturers. While there were occasionally sounds indicating that something was going on in the insulator prior to catastrophic failure, there was no change in the force deflection curve of the test. While there were slight changes in the damping and frequency of the insulators as the loading increased, the changes were small and did not indicate degradation of the insulator. Two failure modes were observed: failure of the lower flange and shear failure at the tube-flange connection. In one case the shear failure was in the bond to the flange and in the other it was in the tube adjacent to the bonding material. In the unbonded tube, there was clear friction damping. In bonded tubes, the presence of friction damping needs further investigation
The American Society of Civil Engineers (ASCE) Sub-Committee on Disaster Resilience of Structures... more The American Society of Civil Engineers (ASCE) Sub-Committee on Disaster Resilience of Structures and Infrastructures initiated a testbed study on Resilience-Based design (RBD) considering two critical strategic structures (Town Hall and Hospital), a University Campus and the water distribution network of a small town. These structures were chosen because of the widespread interest in critical structures and infrastructures. In particular, the first two structures are considered critical, because they must not only survive the shaking, but must remain in operation. They require the largest investment of resources to insure that they can provide services following an earthquake. The test bed study will be developed using discrete event simulation models which are going to be calibrated using real data collected in the field. The development of these test beds will facilitate the comparison among different resilience frameworks which are available in literature. The paper presents an overview and problem definition of a hospital testbed which intends to help move the earthquake engineering community another step toward the realization and implementation of resilience-based design strategies.
Two control systems, an active tendon system and an active mass damper system are selected for st... more Two control systems, an active tendon system and an active mass damper system are selected for study for possible real structural implementation. Presented in this paper are simulation results when these systems in simple configurations are applied to a scaled-down six-story frame building in the laboratory. These results show that a simple active control system can be effective in response control of complex structures under earthquake loads. Relative merits of the two active systems are compared together with a discussion of some general control requirements expected in performing the experiments.
20th Analysis and Computation Specialty Conference - Proceedings of the Conference, 2012
ABSTRACT Weakening and damping of structures has proven to be an effective method for mitigating ... more ABSTRACT Weakening and damping of structures has proven to be an effective method for mitigating the structure's response. This approach has drawn further attention after the invention of negative stiffness device (NSD), developed by the authors. Preliminary analytical and experimental studies reported on the NSD have revealed that by adding the NSD to a single story structure the base shear demands and peak acceleration of the main structure are reduced significantly and the inter-story deformations are contained by ...
An isolation system consisting of sliding Teflon bearings and displacement control devices is des... more An isolation system consisting of sliding Teflon bearings and displacement control devices is described for the seismic protection of bridges. The system utilizes multidirectional Teflon bearings for accommodating thermal movements and for providing the isolation mechanism and displacement control devices which exhibit bilinear behavior with controlled stiffness and characteristic strength. The devices provide rigidity for service loads below their characteristic strength and restoring force and energy dissipation for strong earthquake forces.
A comprehensive investigation to study the effect of flexible floor diaphragms on the inelastic s... more A comprehensive investigation to study the effect of flexible floor diaphragms on the inelastic seismic response of reinforced concrete buildings is presented. The study used a combined experimental and analytical approach, the details of which are described. The paper presents extended descriptions and results of an experimental study of the shaking-table response of a scaled model structure, and its pertinent component tests. The correlation between the analytical predictions obtained using the developed model and the exoerimental responses is examined.
This report describes the results of an experimental study of the behavior of a sliding isolation... more This report describes the results of an experimental study of the behavior of a sliding isolation system with a spherical surface installed in a flexible structure with large aspect ratio. A series of shake table tests was conducted and the results show a marked increase ...
<p><strong>Title</strong>: Behavior of Braced Steel Frames With Innovative Brac... more <p><strong>Title</strong>: Behavior of Braced Steel Frames With Innovative Bracing Schemes - A NEES Collaboratory Project (NEES-2005-0024)</p> <p><b>Year Of Curation: </b>2011</p> <p><b>Description: </b>This project intends to generate data on the behavior of braced steel frames with emphasis on a novel configuration called a zipper frame. In a zipper frame, the unbalanced forces set up as a result of buckling of the inverted V braces in compression are taken by an additional vertical element, leading to nearly simultaneous buckling of all stories. Look in the "Directory....PDF" file in Project Documentation to see a list of all files and their location for the Georgia Tech experiments.</p> <p><b>Award: </b>http://www.nsf.gov/awardsearch/showAward?AWD_ID=0324277</p> <p><b>PIs & CoPIs: </b>NSF Pre-NEES Program CMS-0324629</p> <p><b>Dates: </b>October 01, 2003 - April 28, 2009</p> <p><b>Organizations: </b><br /> Georgia Institute of Technology, GA, United States<br /> State University of New York at Buffalo, NY, United States<br /> University of California, Berkeley, CA, United States<br /> University of California, San Diego, CA, United States<br /> University of Colorado at Boulder, CO, United States</p> <p><b>Facilities: </b>Georgia Institute of Technology, GA, United States<br /> State University of New York at Buffalo, NY, United States<br /> University of California, Berkeley, CA, United States<br /> University of California, San Diego, CA, United States<br /> University of Colorado at Boulder, CO, United States</p> <p><b>Sponsor: </b>NSF - n/a - 0324277</p> <p><b>Keywords: </b>Braced Frames, Struts, Zipper Struts, Steel</p> <p><b>Publications: </b><br /> &qu [...]
Linear and non-linear analytical studies were conducted for evaluating the performance of the sou... more Linear and non-linear analytical studies were conducted for evaluating the performance of the southbound separation and overhead bridge at the SR 14/I5 interchange during the Northridge earthquake of January 17, 1994. The analyses are focused on potential implications of the spatial variability of ground motion on the collapse of the structure. The influences of vertical ground motion, soil-structure interaction, non-linear contact effects at the expansion joints and abutments, are also examined. The parameter studies help to determine some of the causes of collapse and offer insight in the complex seismic behavior of long multi-span concrete bridges.
Fragility curves are functions which represent the probability that a given structure’s response ... more Fragility curves are functions which represent the probability that a given structure’s response to various seismic (conditions) excitations exceeds performance limit states. As such, fragility curves are a measure of performance in probabilistic terms. The major objectives of MCEER research on fragility information are: (1) developing efficient and accurate methods to calculate fragility curves for structural and nonstructural components and for global assemblies (systems); (2) establishing fragility information as a base for performance-based design, cost and loss assessment, and decision policies; (3) developing optimal strategies for seismic rehabilitation based on cost-benefit analysis; and (4) establishing rational performance limit states based on interaction between engineering and socioeconomic issues.
1 Assistant Professor, Department of Civil Engineering, Indian Institute of Technology, New Delhi... more 1 Assistant Professor, Department of Civil Engineering, Indian Institute of Technology, New Delhi, India 2 Professor, Department of Civil Engineering, State University of New York, Buffalo, NY 14260 3 Associate Professor, Department of Civil Engineering, State University of New York, Buffalo, NY 14260 In reinforced concrete masonry shear walls with ungrouted cells, the longitudinal steel reinforcing bars are not bonded (unbonded) to the neighboring masonry. As a result, the steel strains as well as forces are governed by the relative displacements of the end anchorages and are, therefore, dependent on the deformations of the entire wall. After the development of the first flexural crack at the base, the in-plane lateral load is resisted primarily by arch action (tie-strut mechanism) due to the absence of bonding in such walls, as opposed to beam action which is the dominant load resisting mechanism for shear walls with bonded reinforcement. Further, the flexural cracking causes a pa...
The importance of nonstructural components has been demonstrated during past seismic events since... more The importance of nonstructural components has been demonstrated during past seismic events since damage to such components can be not only a critical threat to life safety in extreme cases, but also result in a substantial reduction of functionality of buildings. Current standards do not explicitly provide guidance for the seismic design of a suspended ceiling system, one of important nonstructural components in buildings, due to their complex construction. In order to understand the dynamic behavior of a suspended ceiling system, full scale shake table tests of 20ft. × 50ft. and 20ft. × 20ft. ceiling systems were conducted at University at Buffalo. Identified failure modes that describe functionality of the system include (i) failure of perimeter connections, (ii) failure of grid component connections, (iii) fallen panels, and (iv) system collapse. Based on the observed failure mechanisms and the physical properties of a ceiling structure, several simplified uniaxial analytical mo...
The concept of Disaster Resilience has received considerable attention in recent years and it is ... more The concept of Disaster Resilience has received considerable attention in recent years and it is increasingly used as an approach for measuring response of communities to natural disasters. Recently a framework named PEOPLES has been developed by MCEER to measure performance of communities to natural disasters. The method includes seven dimensions that include both technical and socio-economic aspects. All resilience dimensions and their respective indices to measure community performances are obviously interdependent. As first step, the physical dimension has been implemented in software and indices have been proposed to measure performance of buildings and lifelines. This paper tries to focus on developing methodologies to consider interdependencies between buildings (e.g. hospitals, strategic buildings, etc) and lifelines (road networks, etc.). An approach considering network interdependencies have been developed which is based on the time series analysis of the restoration curve...
This paper presents preliminary results and analysis of a cantilever load test on two types hollo... more This paper presents preliminary results and analysis of a cantilever load test on two types hollow-core composite insulators and summarizes the response of the insulators to different types of loading. The tube of the insulator is a cylindrical shell of fibers-glass in a resin-based matrix with aluminum flange end fittings. The integrity of the tube-flange connection is checked for leaks, slip, damage, and bond degradation. Tests indicate that he actual cantilever load causing failure was much higher than the rated SML provided by the manufacturers. While there were occasionally sounds indicating that something was going on in the insulator prior to catastrophic failure, there was no change in the force deflection curve of the test. While there were slight changes in the damping and frequency of the insulators as the loading increased, the changes were small and did not indicate degradation of the insulator. Two failure modes were observed: failure of the lower flange and shear failure at the tube-flange connection. In one case the shear failure was in the bond to the flange and in the other it was in the tube adjacent to the bonding material. In the unbonded tube, there was clear friction damping. In bonded tubes, the presence of friction damping needs further investigation
The American Society of Civil Engineers (ASCE) Sub-Committee on Disaster Resilience of Structures... more The American Society of Civil Engineers (ASCE) Sub-Committee on Disaster Resilience of Structures and Infrastructures initiated a testbed study on Resilience-Based design (RBD) considering two critical strategic structures (Town Hall and Hospital), a University Campus and the water distribution network of a small town. These structures were chosen because of the widespread interest in critical structures and infrastructures. In particular, the first two structures are considered critical, because they must not only survive the shaking, but must remain in operation. They require the largest investment of resources to insure that they can provide services following an earthquake. The test bed study will be developed using discrete event simulation models which are going to be calibrated using real data collected in the field. The development of these test beds will facilitate the comparison among different resilience frameworks which are available in literature. The paper presents an overview and problem definition of a hospital testbed which intends to help move the earthquake engineering community another step toward the realization and implementation of resilience-based design strategies.
Two control systems, an active tendon system and an active mass damper system are selected for st... more Two control systems, an active tendon system and an active mass damper system are selected for study for possible real structural implementation. Presented in this paper are simulation results when these systems in simple configurations are applied to a scaled-down six-story frame building in the laboratory. These results show that a simple active control system can be effective in response control of complex structures under earthquake loads. Relative merits of the two active systems are compared together with a discussion of some general control requirements expected in performing the experiments.
20th Analysis and Computation Specialty Conference - Proceedings of the Conference, 2012
ABSTRACT Weakening and damping of structures has proven to be an effective method for mitigating ... more ABSTRACT Weakening and damping of structures has proven to be an effective method for mitigating the structure's response. This approach has drawn further attention after the invention of negative stiffness device (NSD), developed by the authors. Preliminary analytical and experimental studies reported on the NSD have revealed that by adding the NSD to a single story structure the base shear demands and peak acceleration of the main structure are reduced significantly and the inter-story deformations are contained by ...
An isolation system consisting of sliding Teflon bearings and displacement control devices is des... more An isolation system consisting of sliding Teflon bearings and displacement control devices is described for the seismic protection of bridges. The system utilizes multidirectional Teflon bearings for accommodating thermal movements and for providing the isolation mechanism and displacement control devices which exhibit bilinear behavior with controlled stiffness and characteristic strength. The devices provide rigidity for service loads below their characteristic strength and restoring force and energy dissipation for strong earthquake forces.
A comprehensive investigation to study the effect of flexible floor diaphragms on the inelastic s... more A comprehensive investigation to study the effect of flexible floor diaphragms on the inelastic seismic response of reinforced concrete buildings is presented. The study used a combined experimental and analytical approach, the details of which are described. The paper presents extended descriptions and results of an experimental study of the shaking-table response of a scaled model structure, and its pertinent component tests. The correlation between the analytical predictions obtained using the developed model and the exoerimental responses is examined.
This report describes the results of an experimental study of the behavior of a sliding isolation... more This report describes the results of an experimental study of the behavior of a sliding isolation system with a spherical surface installed in a flexible structure with large aspect ratio. A series of shake table tests was conducted and the results show a marked increase ...
<p><strong>Title</strong>: Behavior of Braced Steel Frames With Innovative Brac... more <p><strong>Title</strong>: Behavior of Braced Steel Frames With Innovative Bracing Schemes - A NEES Collaboratory Project (NEES-2005-0024)</p> <p><b>Year Of Curation: </b>2011</p> <p><b>Description: </b>This project intends to generate data on the behavior of braced steel frames with emphasis on a novel configuration called a zipper frame. In a zipper frame, the unbalanced forces set up as a result of buckling of the inverted V braces in compression are taken by an additional vertical element, leading to nearly simultaneous buckling of all stories. Look in the "Directory....PDF" file in Project Documentation to see a list of all files and their location for the Georgia Tech experiments.</p> <p><b>Award: </b>http://www.nsf.gov/awardsearch/showAward?AWD_ID=0324277</p> <p><b>PIs & CoPIs: </b>NSF Pre-NEES Program CMS-0324629</p> <p><b>Dates: </b>October 01, 2003 - April 28, 2009</p> <p><b>Organizations: </b><br /> Georgia Institute of Technology, GA, United States<br /> State University of New York at Buffalo, NY, United States<br /> University of California, Berkeley, CA, United States<br /> University of California, San Diego, CA, United States<br /> University of Colorado at Boulder, CO, United States</p> <p><b>Facilities: </b>Georgia Institute of Technology, GA, United States<br /> State University of New York at Buffalo, NY, United States<br /> University of California, Berkeley, CA, United States<br /> University of California, San Diego, CA, United States<br /> University of Colorado at Boulder, CO, United States</p> <p><b>Sponsor: </b>NSF - n/a - 0324277</p> <p><b>Keywords: </b>Braced Frames, Struts, Zipper Struts, Steel</p> <p><b>Publications: </b><br /> &qu [...]
Linear and non-linear analytical studies were conducted for evaluating the performance of the sou... more Linear and non-linear analytical studies were conducted for evaluating the performance of the southbound separation and overhead bridge at the SR 14/I5 interchange during the Northridge earthquake of January 17, 1994. The analyses are focused on potential implications of the spatial variability of ground motion on the collapse of the structure. The influences of vertical ground motion, soil-structure interaction, non-linear contact effects at the expansion joints and abutments, are also examined. The parameter studies help to determine some of the causes of collapse and offer insight in the complex seismic behavior of long multi-span concrete bridges.
Uploads
Papers by Andrei Reinhorn