and Nonstructural Performance
Stephen Mahin (UCB), Thrust Leader
The ultimate goal of Thrust Area 5 is to develop the fundamental knowledge and understanding of the performance of structural and nonstructural components and systems (including uncertainty and randomness) needed to develop and assess computational tools for simulating performance of buildings and bridges. Performance characterization includes conventional representations such as strength and deformation capacity, but also includes damage parameters such as concrete spalling and its relation to required repair. As such, research efforts in this thrust area include:
1) Review, synthesis and evaluation of prior work related to specific aspects of structural and non-structural performance,
2) Identification of robust parameters for characterizing and quantifying performance and of structural and nonstructural components and systems,
3) Development of conceptual and theoretical models to evaluate the performance of structural and nonstructural elements as well as complete systems, and
4) Conduct tests and analyses, as necessary, to provide data needed to fill essential knowledge gaps as well as to assess computational tools and models being developed elsewhere within PEER to characterize performance.As such, activities being undertaken in Thrust Area 5 have been carefully integrated with tasks in other areas. Investigators in Thrust Areas 4 and 5 are working closely together to help improve the fidelity and resolution with which structural performance can be predicted. The integrative testbeds for bridges and buildings (coordinated in Task Area 3) are being provided data developed by investigators in Thrust Area 5, and knowledge gaps identified in the testbeds related to structural and nonstructural performance will be addressed in Thrust Area 5. Component level tests performed in prior years within Task Area 5 are being extended now to include tests and analyses of more complex systems subjected to dynamic loading in a joint effort with Thrust Area 4 to assess the capabilities and reliability of OpenSees platform and the simulation models developed to date. In addition, investigators in Thrust Area 5 are working to characterize performance of structural and nonstructural elements in a manner consistent with the overall PBEE evaluation and design methodology being developed in Thrust Area 3 and the performance criteria and loss measures being developed in Thrust Area 1. Activities in Thrust Area 5 parallel activities in Thrust Area 2 (aimed at providing similar information on the performance of geotechnical systems and structural foundations).
Damage Assessment of Building Nonstructural Components—5242002
Eduardo Miranda (Stanford/F), Shahram Taghavi (Stanford/GS)
The objective of this study is to develop information and procedures to estimate the seismic performance of nonstructural components. This involves
- the estimation of Engineering Demand Parameters (EDP) that are relevant to nonstructural components, which usually involve additional information to that required to estimate the performance of structural components;
- the development of fragility functions that enable the estimation of the probability of being in different damage states as a function of EDPs;
- the development of loss functions that permit the estimation of economic losses as a function of the damage state. This project is being conducted in connection with the seven-story reinforced concrete building PEER testbed structure. Loss estimation associated to structural components is being conducted in another project (Project # 1182002).
RC Frame Validation Tests—5252002
Jack Moehle (UCB/F), Yoon Bong Shin (UCB/GS), Wassim Michael Ghannoum (UCB/GS), Tony Yang (UCB/GS), Jeffrey Liu (UCB/PD)
The goal of this project is to develop validation data and nonlinear models for nonlinear response, component failure mechanisms, and internal force redistribution as collapse occurs in a building frame representative of older concrete construction.
Bridge Bent Shaking Table Validation Tests—5272002
Steve Mahin (UCB/F), Andreas Espinoza (UCB/GS), Mahmoud Hachem (UCB/GS), Eric Anderson (UCB/GS), Peter Symonds (UCB/US)
The goal of this project is to conduct a test on a simple reinforced concrete model bridge system, resulting in development of validation data on nonlinear response, component yielding/damage, and internal force redistribution during ductile response.
Database and Acceptance Criteria for Column Tests—5282002
Marc Eberhard (UW/F), Mike Berry (UW/GS), Haili Camarillo (UW/GS)
The goal of this project is to develop and calibrate tools for assessing reinforced concrete column seismic performance, including data and models for both seismically conforming (ductile) and non-conforming (brittle) columns.
Performance Characteristics of Bench and Shelf-Mounted Equipment—5292002
Tara Hutchinson (UCI/F), Gerard Pardoen (UCI/F), Roberto Villaverde (UCI/F), Robert Kazanjy (UCI/O), Samit Ray Chaudhuri (UCI/GS), Jake Bazen (UCI/US)
Modeling and evaluating the response of nonstructural equipment and contents is important for determining the overall economic losses associated with an earthquake event. The particular objectives of studies at UCI, which complement studies by researchers at UCB (Makris), are to characterize the seismic performance of bench and shelf-mounted equipment and contents within a biological/chemical building. In this case, the emphasis is on equipment and contents present in the UC Science building. Our approach, which contributes to the development of performance-based design methodologies, is to develop analytical seismic fragility curves describing the probability of exceedance of a limit state (damage measure DM) given an input (an engineering demand parameter EDP). Experimental data is being used to provide dynamic characterization of the supporting bench system and response information regarding the equipment-bench interface.
Performance Characteristics of Building Contents—5302002
Nicos Makris (UCB/F), Dimitrios Konstantinidis (UCB/GS), Margarita Constantinides (UCB/GS)
In this project experimental and analytical studies are underway to examine the seismic vulnerability of free standing and anchored equipment located within buildings with several floor levels. The equipment of interest are low-temperature refrigerators, freezers, incubators and other heavy equipment of the Life Science Addition (LSA) building on the UC Berkeley campus.
The dynamic behavior of either free-standing or anchored equipment is very sensitive to the characteristics of the base input (mainly acceleration amplitudes and frequency content), the frictional characteristics of the equipment-base interface, the restrainer strength and ductility and the structural rigidity of the equipment.
Performance Evaluation of Gypsum Wallboard Partitions—5322002
André Filiatrault (UCSD/F), José Restrepo (UCSD/F), Andrew Bersofsky (UCSD/GS)
The objectives of this project are to develop data and models to characterize the performance of gypsum wallboard partitions, of the type common to modern office, hotel, and laboratory buildings.
RC Shear Wall Model Implementation and Validation—5332002
John Wallace (UCLA/F), Kutay Orakcal (UCLA/GS), Leonardo Massone (UCLA/GS)
The project involves development and calibration of a robust model for reinforced concrete shear walls and implementation of the model into the OpenSees platform. A multiple-component-in-parallel model (or multiple-vertical-line-element model) has been selected for the modeling effort. Cyclic material relations used for reinforcing steel and concrete will be employed, and will address gap opening and closing behavior. Simulation results for both global and local responses obtained using the model will be compared with experimental results obtained for moderate-scale shear wall tests, such as those reported by Thomsen and Wallace (1995) and Taylor and Wallace (1995). An important aspect of the project will involve work to address nonlinear shear behavior and the linkage of shear strength degradation with flexural ductility. The potential to expand the model to address flanged walls by using shape functions to describe nonlinear strain distributions for wall flanges, and sub-elements to model wall openings, will be investigated.
Assessment and Design of Enhanced Performance Bridge Systems—5342002
Steve Mahin (UCB/F), Junichi Sakai (UCB/PD)
The overall goal of this study is to examine and assess various design concepts for enhancing the seismic performance of new bridge structures of the type being considered by PEER. Promising design details will be assessed though dynamic shaking table tests as well as through more extensive nonlinear dynamic analyses using the OpenSees computational platform. In particular, the potential for reducing residual displacements of bridges following severe earthquakes will be examined through the use of special plastic hinge regions containing combinations of unbonded, prestressed and mild reinforcement. Other design approaches utilizing high performance concrete, foundation details that permit rocking behavior, or other enhancements will be examined in concert with others working within the PEER Center. The PEER PBEE methodology will be utilized to quantify the benefits of these enhanced systems in comparison with conventional bridge construction in use today. The goal of this project would be to demonstrate the value of the PEER methodology for a specific application, and thereby to accelerate the adoption of new bridge design technologies into practice.
Validation of Simulation and Performance Models of RC Joints—5352002
Dawn Lehman (UW/F), John Stanton (UW/F), George Gimas (UW/US), Meredith Anderson (UW/GS)
The goals of the study are to develop practical simulation and performance models for beam-column joints that lack transverse reinforcement. The specific objectives, which constitute the research tasks and deliverables, include:
- Development of simple simulation tools for immediate use by the profession. (Task 1)
- Validation of more advanced simulation tools. (Task 2)
- Development of performance models appropriate for each type of simulation model, including acceptance criteria. (Task 3)
- Development of guidelines for the use of each pair of simulation and performance models. (Task 4)
Simulation of Enhanced-Performance Post-Tensioned Bridge Piers—5362002
Sarah Billington (Stanford/F)
The overall goal of this study is to demonstrate how the PEER PBEE methodology can accelerate the adoption of new bridge design technologies by quantitatively assessing the performance enhancement provided by these technologies. The first detailed objective is to identify the damage measures (DMs) of unbonded post-tensioned (UBPT) bridge piers (an enhanced performance system) that relate to decision variables (DVs) relevant to bridge performance, such as safety, functionality and repair time. Promising engineering demand parameters (EDPs) that characterize and quantify the appropriate DMs of unbonded post-tensioned bridge piers will then be identified. The second objective is to simulate recent cyclic and seismic experiments on UBPT bridge piers using detailed finite element analyses as well as simple macro-models with the goal of modeling and predicting accurately various EDPs.
Analytical Models for Electrical Equipment Connected by Rigid Buses—Lifelines 401b
Armen Der Kiureghian (UCB/F), Jerome Sackman (UCB/F), Junho Song (UCB/GS)
This project extends previous work on analytical modeling of the interaction effect between electrical substation equipment connected by rigid buses. The goal is make refinements to interaction analysis by accounting for the prevailing uncertainties in the ground motion and equipment characteristics. Comparison with tests conducted by other PEER researchers are made.
Substation Equipment Interaction-Experimental Models of Rigid Bus Connectors—Lifelines 402
André Filiatrault (UCSD/F), Christopher Stearns (UCSD/GS)
The three main objectives are:
- Perform quasi-static testing of rigid buses of different shapes, including offsets and bends.
- Coordinate with on-going projects 403, 404 and 408 to refine properties and representation of generic equipment, and modification of input motions of equipment appendages
- Perform shake table tests of several pairs of refined generic equipment interconnected by rigid bus of different shapes, including improved connectors.
Improvements to Modeling Substation Equipment—Lifelines 404
Gerard Pardoen (UCI/F), Charles Hamilton (UCI/PD), Rick Tavares (UCI/PD), Davis Fetter (UCI/US), Julie Manson UCI/US)
Utilities use different types of substation equipment that have dynamic characteristics that are not well known for many classes of equipment. Manufacturer differences in design, method of structural support, physical dimensions, voltage class differences as well as differences at the component level are just some of the features that introduce variations of dynamic behavior. Although utilities have been specifying that equipment be seismically qualified by analysis for many years, there is uncertainty in the dynamic properties and methods of modeling used in these analyses.
Seismic Qualification and Fragility Testing of 500kV Disconnect Switches—Lifelines 411
Gregory Fenves (UCB/F), Shakhzod Takhirov (UCB/O), Don Clyde (UCB/O)
Project 411 consisted of seismic qualification and fragility testing of 500kV disconnect switch. Qualification by shake table testing is intended to demonstrate that the disconnect switch and appurtenant equipment satisfy the requirements of IEEE 693-1997 at the high qualification level. Tests at two RRS levels (0.25g, pga and 0.5g, pga), the Performance Level (1.0g, pga), and fragility tests are included in the test program.
Database of Seismic Parameters of Equipment in Substations—Lifelines 413
Dennis Ostrom (I)
Electrical substations consist of many pieces of equipment that are vulnerable to earthquakes. Vulnerability depends on a variety of parameters including equipment type, voltage, manufacturer, seismic design criteria, installation and anchorage, foundations and soil conditions, and connection to other equipment. In order to be able to make accurate and standardized estimates of potential losses in earthquakes and to set priorities for equipment upgrades and replacements, an accurate database of the relevant seismic-performance parameters of substation equipment is needed. In this project, a comprehensive procedure for compiling seismic performance parameters will be developed and documented. The experience gained in assessing seismic vulnerability of substation equipment in previous PEER Lifelines Program research will be incorporated.