New Technical Reports
Fragility Analysis of Water Supply Systems
By A. Jacobson and M. Grigoriu, MCEER-08-0009, March 10, 2008, 154 pages, $25.00
This report describes a procedure to assess the seismic performance of water supply systems. Seismic hazard models were developed to generate earthquake activity at single and multiple sites. Methodologies to obtain the fragility of a given pipeline were developed, including several hazard conditions: continuous and jointed pipelines subjected to seismic waves, pipelines subjected to PGD hazards, and pipelines subjected to fault displacements. Information was integrated into an algorithm that used Monte Carlo simulation to determine the damage states of individual components, and hydraulic analyses to estimate the performance of the damaged system. The algorithm was applied to a sample water supply system, and fragility curves were produced under different limit states. In addition, a procedure to estimate the life cycle damage and cost over the life span of the system was presented.
Experimental Investigation of Full-Scale Two-Story Steel Plate Shear Walls with Reduced Beam Section Connections
B. Qu, M. Bruneau, C.-H. Lin and K.-C. Tsai, MCEER-08-0010, March 17, 2008, 196 pages, $30.00
This report describes an experimental research program on Steel Plate Shear Walls (SPSWs), conducted in collaboration with the National Center for Research on Earthquake Engineering (NCREE) in Taipei, Taiwan. The research project investigated the replaceability of infill panels following an earthquake, the behavior of a repaired SPSW in a subsequent earthquake, and the seismic performance of intermediate beams. The test specimen was a two-story SPSW that had an intermediate composite beam with reduced beam section (RBS) connections. In Phase I, the specimen was pseudodynamically tested and subjected to three ground motions of progressively decreasing intensity. The buckled panels were replaced by new panels prior to subjecting the specimen to a subsequent pseudodynamic test and cyclic test to failure in Phase II. The results showed that replacing the buckled infill panels was a viable option that would provide adequate resistance against future earthquakes.
Seismic Evaluation and Rehabilitation of Critical Components of Electrical Power Systems
By S. Ersoy, B. Feizi, A. Ashrafi and M. A. Saadeghvaziri, MCEER-08-0011, March 17, 2008, 286 pages, $35.00
The goal of this study was to assess the seismic performance of electrical power substations and develop rehabilitation measures for existing substations using advanced technologies. A comprehensive study was conducted that included detailed finite element analyses of different types of transformers and bushings, as well as parameter and experimental studies of the friction pendulum system for use as a possible mitigation approach. Simplified models were developed and interaction among transformer-bushing and interconnecting equipment was investigated. Internal packaging of transformers was evaluated and its seismic performance was qualitatively assessed. Experimental studies of critical substation components were performed in collaboration with the National Center for Research on Earthquake Engineering (NCREE) in Taiwan. The results demonstrate that base isolation using a friction pendulum system is a viable rehabilitation option for substations.
Seismic Behavior and Design of Boundary Frame Members of Steel Plate Shear Walls
By B. Qu and M. Bruneau, MCEER-08-0012, April 26, 2008, 276 pages, $35.00
This report presents the results of an analytical study to investigate the behavior of horizontal and vertical boundary frame members that may impact the performance of Steel Plate Shear Walls (SPSWs). New analytical models were developed for horizontal boundary frame members to calculate the plastic moment and resulting strength reduction caused by biaxial internal stress conditions, and to revisit and develop improved capacity design procedures that account for them. The models incorporate observations made in a companion experimental study (see Technical Report MCEER-08-0010). Next, the adequacy of a flexibility limit for the design of vertical boundary frame members specified in current design codes was assessed using the new models. The contribution of the boundary frame moment resisting action and infill panel tension field action to the overall plastic strength of SPSWs was investigated.
Development and Appraisal of a Numerical Cyclic Loading Protocol for Quantifying Building System Performance
By A. Filiatrault, A. Wanitkorkul and M. Constantinou, MCEER-08-0013, April 27, 2008, 142 pages, $25.00
The objective of this study was to develop a numerical cyclic loading protocol, based on available experimental and numerical studies, to quantify building system performance. The report reviews and compares existing experimental loading protocols that have been developed for quasi-static cyclic testing of structural components and systems. A numerical cyclic loading protocol is then proposed for quantifying building system performance. Next, a sensitivity analysis of the influence of the number of repeating cycles of the proposed numerical cyclic loading protocol on the equivalent elastic lateral stiffness and viscous damping properties of a 4-story reinforced concrete building model is investigated. Based on the results, the proposed numerical cyclic loading protocol is used in a simplified capacity spectrum methodology to estimate the seismic response of two 4-story and one 12-story building models.
Structural and Nonstructural Earthquake Design: The Challenge of Integrating Specialty Areas in Designing Complex, Critical Facilities
By W.J. Petak and D.J. Alesch, MCEER-08-0014, April 30, 2008, 74 pages, $25.00
This report explores the challenges faced by engineers and architects in integrating structural and nonstructural elements in the design of earthquake resistant buildings. The authors review the traditional roles and responsibilities of various participants in constructing a modern building, and explore impediments to incorporating nonstructural design into engineering practice. Several possible solutions are proposed, including the creation of a new profession called a “master builder” who would serve as a building systems integrator. Legislation such as California’s SB 1953, which brought the problems associated with integrating architecture, structural engineering, and the design and installation of nonstructural components of acute care hospitals into sharp focus, may provide some incentive to academic institutions to broaden current curriculums to be more in line with the needs of professional practice in this area.
Seismic Performance Evaluation of Water Supply Systems
By Y. Wang and T.D. O’Rourke, MCEER-08-0015, May 5, 2008, 398 pages, $35.00
This report describes an evaluation process for simulating the seismic performance of large geographically distributed water supply systems and characterizing their performance in terms of reliability and serviceability. The evaluation process uses probabilistic seismic hazard analysis tools, theoretical and empirical relationships of pipeline responses, hydraulic analysis of heavily damaged water networks, and multi-scale simulations of complex water systems. The process provides information for decision makers to assess the economic and social impacts of lifeline disruptions due to earthquakes, and works in combination with a computer code, Graphical Iterative Response Analysis for Flow Following Earthquakes (GIRAFFE) developed by the authors to simulate heavily damaged pipeline networks. The simulation results are presented in GIS format. The methodology was used to evaluate the seismic performance of the Los Angeles Department of Water and Power (LADWP) water supply system. The results show that the five water districts in the LADWP have significantly different seismic risks and deteriorate to various extents after a 24-hour period following an earthquake. These differences are consistent with the geographical position of the districts in relationship to the faults and their capacity for water storage.
Seismic Response Modeling of Water Supply Systems
By P. Shi and T.D. O’Rourke, MCEER-08-0016, May 5, 2008, 352 pages, $35.00
This report presents a comprehensive model for simulating the earthquake performance of water supply systems. The model is developed in conjunction with the water system operated by the Los Angeles Department of Water and Power (LADWP) and validated through comparisons to observations and flow measurements following the 1994 Northridge earthquake. The performance of damaged water supply systems is simulated by a hydraulic network analysis that uses an iterative approach to isolate the network nodes with negative pressures. The isolation process accurately accounts for flows and pressures in the damaged water networks. The seismic performance of the LADWP system is simulated using a multiscale technique in which the LADWP trunk system is explicitly accounted for, while the remaining distribution lines are simulated through fragility curves relating demand to repair rate. The repair rate, in turn, is correlated with peak ground velocities, and fragility curves are developed on the basis of distribution network simulations. The proposed model is integrated into computer code, Graphical Iterative Response Analysis for Flow Following Earthquakes (GIRAFFE) developed by the authors, which presents the simulation results in GIS format.
Numerical and Experimental Studies of Self-Centering Post-Tensioned Steel Frames
By D. Wang and A. Filiatrault, MCEER-08-0017, May 12, 2008, 436 pages, $60.00
This report presents a numerical and experimental study to evaluate and compare the seismic performance of Self-Centering Post-Tensioned (SCPT) steel frames and conventional Steel Moment Resisting Frames (SMRF). A methodology for designing SCPT structures is developed and used to retrofit an existing four-story SMRF medical facility located in Northridge, California. A Relative Performance Index (RPI) is proposed to compare the enhancement in the seismic response of SCPT’s to the SMRF’s. Numerical simulations and shake table tests were carried out on two scaled 3-story 2-bay SCPT and SMRF building prototypes based on the medical facility. The study indicates that the seismic floor displacements of SCPT and SMRF are alike, while absolute floor accelerations are lower when self centering systems are implemented. Moreover, while yielding in the beam-to-column connections of the SMRF are observed, only yielding of the sacrificial devices in the self centering system of the SCPT occurred during the strongest ground motions considered.
Development, Implementation and Verification of Dynamic Analysis Models for Multi-Spherical Sliding Bearings
By D.M. Fenz and M.C. Constantinou, MCEER-08-0018, 8/15/2008, 308 pages, $35.00
This report describes the formulation, implementation and validation of multi-spherical sliding bearing models proposed for response history analysis of double and triple Friction Pendulum (FP) bearings. These bearings exhibit hysteretic behavior that is more complex than current seismic isolation devices. Since double FP bearings behave like two single concave FP bearings connected in series, the proposed model considers a series arrangement of single FP elements. Additionally, it is shown that a series arrangement can be used to capture the behavior of triple FP bearings provided that the model parameters are appropriately modified. The proposed models can be implemented in currently available structural analysis programs such as SAP2000 and 3D-BASIS. The FP bearing models presented in this report are verified by comparing the results obtained from shake table testing of a quarter-scale six-story building model to those predicted by response history analysis. Good agreement is observed even in cases of extreme response, which attest to the robustness and validity of the proposed models.
Performance Assessment of Conventional and Base-Isolated Nuclear Power Plants for Earthquake and Blast Loadings
By Y-N Huang, A.S. Whittaker and N.Luco, MCEER-08-0019, October 28, 2008, 400 pages, $35.00
This study assesses the performance of conventional and base isolated Nuclear Power Plant (NPP) reactor buildings subjected to earthquake and blast loadings. Three base isolation systems, friction pendulum, lead-rubber and low damping rubber bearings, are studied. A new procedure for probabilistic seismic risk assessment of structures is proposed, built on the methodology presented in the ATC-58 Guidelines and the Zion method. The seismic performance assessment confirms the ability of base isolation systems to reduce spectral demands on secondary systems. Response-history analyses of conventional and base isolated reactor buildings to external blast loads are performed. The spectral demands on the secondary systems in the base isolated reactor building due to air blast loadings are greater than for a conventional reactor building, but much smaller than the demands associated with the safe shutdown earthquake loading. The base isolation systems are shown to be effective at filtering out high acceleration-high frequency ground shock loading.
Building Inventory Compilation for Disaster Management: Application of Remote Sensing and Statistical Modeling
By P.Sarabandi, A.S. Kiremidjian, R.T. Eguchi and B.J. Adams, MCEER-08-0025, November 20, 2008, 132 pages, $25.00
This report introduces a methodology to extract spatial, geometric and engineering attributes of buildings using single high-resolution satellite images. Rational Polynomial Coefficients (RPC) are used to generate three dimensional models of buildings showing height, footprint, and shape information. Geometric information defining the sensor’s orientation is used in conjunction with the RPC projection model to generate digital elevation models. The report describes how the location and height of a structure are extracted by measuring the image coordinates for the corner of a building at ground level and its corresponding roof-point coordinates, and using the relationship between image-space and object-space together with the sensor’s orientation. The implementation of the algorithm and its application to the City of London are described. In addition, a methodology based on a multinomial logistic model is developed to infer the marginal probability distributions of the structural type and occupancy of a building. Datasets collected for southern California are used to train the models and establish inference rules to predict the engineering parameters of the buildings in the region. The predictive capability of the model is shown through the computation of the marginal probability distribution for a sample building.
New Experimental Capabilities and Loading Protocols for Seismic Qualification and Fragility Assessment of Nonstructural Systems
By R. Retamales, G. Mosqueda, A. Filiatrault and A. Reinhorn, MCEER-08-0026, November 24, 2008, 354 pages, $35.00
This report describes the new experimental testing capabilities provided by the University at Buffalo Nonstructural Component Simulator (UB-NCS). The UB-NCS is composed of a two-level testing frame that can subject full-scale nonstructural components and systems to 3g acceleration, 100 in/s (250 m/s) velocity and ±40 in (±1 m) displacement amplitudes. An innovative set of testing protocols utilizing the UB-NCS capabilities is described for qualification testing and fragility assessment. The protocols complement, and in some cases extend, the capabilities of current protocols such as AC156 and FEMA 461. The UB-NCS testing capabilities are demonstrated through a series of experiments assessing the seismic performance of a full-scale composite hospital emergency room containing typical nonstructural components such as architectural finishes, piping systems and medical equipment. The seismic performance of individual components were evaluated as well as the dynamic interactions between them. The input motions included the proposed loading protocol and simulated building floor motions.
Effects of Heating and Load History on the Behavior of Lead-Rubber Bearings
By Ioannis V. Kalpakidis and Michael C. Constantinou, MCEER-08-0027, December 1, 2008, 290 pages, $35.00
This report presents a comprehensive investigation of the effects of lead core heating and cumulative travel on the behavior of lead-rubber bearings. A literature review and an experimental study of the effects of temperature on the mechanical properties of lead are presented. A theory for predicting the temperature rise of the lead core in lead-rubber bearings subjected to lateral motion is developed based on principles of mechanics. The theory reduces the complex three dimensional thermo-mechanical problem into a numerically solvable initial value problem on the history of temperature of the core and the strength of the bearing. It is then used to establish principles of similarity and scaling that can be used in reduced scale testing of lead-rubber bearings. Studies on the dynamic response of seismically isolated structures using the proposed model demonstrate the importance of accounting for the effects of lead core heating in calculating the peak seismic response of seismically isolated structures.
Experimental and Analytical Investigation of Blast Performance of Seismically Resistant Bridge Piers
By Shuichi Fujikura and Michel Bruneau, MCEER-08-0028 December 8, 2008, 342 pages, $35.00
This report focuses on the protection of highway bridges against earthquake and blast hazards. The results of a previously developed and experimentally validated multi-hazard bridge pier concept consisting of a multi-column pier bent with Concrete-Filled Steel Tube (CFST) columns are briefly presented (see MCEER-07-0005). The performance of the CFST columns is compared to the blast resistance of ductile reinforced concrete (RC) columns and non-ductile RC columns retrofitted with steel jackets, detailed in accordance to current seismic design codes and practices. This report describes the details of the design process and the experimental observations of the prototype bridge pier bent constructed using conventional and retrofitted seismic resistant RC columns. The results from blast experiments are compared with results obtained using simplified analysis methods. Nonlinear dynamic response history analyses are performed to simulate and better understand the behavior of CFST columns under blast loading. The tests on conventional and steel jacket retrofitted seismic resistant RC columns demonstrated the non-ductile behavior of the RC columns under blast loading and that the columns failed in direct shear at their base. Based on experimental and analytical observations, shape factors for the blast pressures acting on circular columns are established.