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This paper presents a general seismic classification procedure for acceleration‐sensitive non‐structural elements (NSEs) based on seismic qualification shake table testing and provides an application example for electrical cabinets in Italy. The proposed seismic classification procedure requires the definition of a set of required response spectra (RRS) for qualification shake table testing defined at different seismic hazard levels and the definition of a formal procedure to generate a test input motion. Each required response spectrum at a given seismic hazard level is then linked to different class levels and the requirements that an NSE should present to achieve each class level are defined. Using this framework, a seismic classification procedure for NSEs is developed for Italy, in which, the RRS are defined according to a peak floor spectral acceleration seismic hazard map of the territory so as to predefine regions in which an NSE belonging to a given class can be installed or not according to either a life safety performance objective or a continuous operation performance objective. Also, the limitations of the proposed seismic classification procedure are outlined. Finally, a nominal application example is presented in which four electrical cabinet specimens were tested on a shake table and their class levels were defined. The results of the application example are used to nominally show how the proposed classification procedure could be applied to discriminate between different types of the same NSE depending on the specific desired application. [ABSTRACT FROM AUTHOR]

The quantification of non‐structural seismic performance factors is a crucial step to improve the seismic performance of non‐structural elements (NSEs). Non‐structural seismic performance factors currently included in modern seismic design provisions are mainly based on engineering judgment and have not been calibrated to meet specific performance objectives. This makes the seismic performance of NSEs designed according to force‐based procedures uncertain at best. Previous studies have proposed a general framework for the quantification of non‐structural seismic performance factors. However, due to the necessity of considering the supporting structure dynamic properties in the estimation of the seismic demand, the required computational overhead can make the process unfeasible in some cases depending on the target supporting structure population and the pursued performance objectives. This paper proposes a procedure to estimate the seismic demand on NSEs for the quantification of non‐structural seismic performance factors that drastically reduces the required computational overhead. The proposed procedure makes use of synthetic floor accelerograms to describe in terms of seismic demand an entire population of supporting structures and ground motion sets. The proposed procedure is validated against a complete multiple‐stripe non‐linear time history analysis by deriving and comparing fragility curves. The results of the validation demonstrate that the proposed procedure is able to derive fragility curves that closely match the ones generated by using a multiple‐stripe analyses with remarkable savings in computational time and output storage size. [ABSTRACT FROM AUTHOR]

Direct displacement-based seismic design has been proposed for pallet-type steel storage racks. Damping models are developed in this study for pallet-type steel storage racks in the down-aisle and cross-aisle directions for use in direct displacement-based seismic design. The damping models are developed using results from reversed cyclic tests at a component level or at a system level. Jacobsen's approach is used to develop a first set of damping models. The damping models are then assessed using results from nonlinear time-history analyses. Finally, the damping models are calibrated using an iterative procedure based on results from nonlinear time-history analyses. [ABSTRACT FROM AUTHOR]

Direct displacement-based seismic design has been recently proposed for the seismic design of non-structural building elements. This paper deals with the development of damping models, relating equivalent viscous damping ratio to drift amplitude, for suspended piping trapeze restraint installations for direct displacement-based seismic design. The damping models are developed using reversed cyclic test data available in the literature. First, damping models are proposed using Jacobsen's equal area approach. The damping models developed using Jacobsen's approach are then assessed and calibrated using nonlinear time history analyses of single degree-of-freedom archetypes representing suspended piping trapeze restraint installations in buildings. [ABSTRACT FROM AUTHOR]

A full-scale, two-story, light-frame wood townhouse building, designed according to modern U.S. engineered seismic design requirements, was tested on two triaxial shake tables operating in unison. The main objective of this experimental study was to determine the dynamic characteristics and the seismic performance of the test building under various base input intensities, representative of both ordinary and near-field ground motions in southern California. The building was tested with and without interior (gypsum wallboard) and exterior (stucco) wall finishes. The test results revealed that the installation of gypsum wallboard to the interior surfaces of structural wood sheathed walls substantially improved the seismic response of the test building. The application of exterior stucco further improved the seismic response of the test building, particularly in its longitudinal direction, where the shear response of low aspect ratio wall piers dominated. These shake table test results provide the evidence of the significant influence that wall finish materials have on the behavior of lateral load-resisting systems in light-frame wood construction. DOI: 10.1061/(ASCE)ST.1943-541X.0000112 CE Database subject headings: Buildings; Gypsum; Seismic tests; Shake table tests; Wood structures. Author keywords: Buildings; Gypsum; Seismic tests; Shake table tests; Wood structures.

The experimental seismic responses of a full-scale two-story light-frame wood townhouse building, designed to modern U.S. engineered seismic design requirements, were compared against the predictions of a new software package entitled seismic analysis package for woodframe structures (SAPWood) developed recently within the NEESWood Project. The main objective of this paper was to verify the accuracy of the predictions from the SAPWood model, which incorporates shear deformations of shear walls as well as cumulative floor displacements caused by the out-of-plane rotations of the floor and ceiling diaphragms. A comparison was conducted on interstory drifts and shear wall deformations for various structural configurations (construction phases) of the test building and excitation levels. Good agreement was found between the numerical predictions and test results for the four different construction phases. The SAPWood model was shown to be a promising numerical tool for predicting the seismic response of light-frame wood structures. DOI: 10.1061/(ASCE)ST.1943-541X.0000086 CE Database subject headings: Seismic analysis; Numerical models; Earthquakes; Frames; Wood structures; Computer software. Author keywords: Seismic analysis; Numerical model; Time history; Earthquakes; Wood structures.

High voltage porcelain bushings mounted on transformers have shown vulnerability during past earthquakes. This is contrary to the generally good performance observed during shake table qualification testing of bushings anchored to a rigid base. The seismic vulnerability of porcelain bushings might be caused by the flexibility of transformer tanks and of bushing attachments. Current seismic qualification guidelines consider an amplification factor of 2.0 between the amplitude of the ground motion and the amplitude of the motion at the base of the bushing. This paper investigates numerically the dynamic response of porcelain bushings mounted on transformer tanks. The results of the numerical study show that large amplification occurs when the fundamental frequency of the porcelain bushing is tuned with the fundamental frequency of the transformer tank. DOI: 10.1061/(ASCE)0733-9445(2006) 132:2(287) CE Database subject headings: Earthquakes; Electrical equipment; Electric transmission structures; Seismic effects.

This paper presents the results of quasi-static bending tests on two different flexible conductors (cables) used to interconnect electrical substation equipment. The main objectives were to observe the flexural response of flexible conductors and to determine their moment-curvature relationships under axial tension. The results of the tests indicate that the force-displacement behavior of the conductors is linear-elastic with negligible hysteretic response. For most combinations of axial tension and lateral displacement, the flexural stiffness is very small, and tends toward the minimum possible flexural stiffness, corresponding to the situation where all the strands are slipping past each other, and are unable to transfer any shear force. Only for very large axial tension values does the flexural stiffness approach the maximum possible flexural stiffness, corresponding to the situation where all the strands are able to transfer longitudinal shear forces over one another, and the conductor section acts as a solid cross section. DOI: 10.1061/(ASCE)0733-9445(2005)131:1(151) CE Database subject headings: Cables; Electric transmission lines; Electrical equipment; Flexural strength; Axial forces; Shear forces.

A simple numerical model to predict the dynamic characteristics, quasistatic pushover, and seismic response of woodframe buildings is presented. In this model the building structure is composed of two primary components: rigid horizontal diaphragms and nonlinear lateral load resisting shear wall elements. The actual three-dimensional building is degenerated into a two-dimensional planar model using zero-height shear wall spring elements connected between adjacent diaphragms or the foundation. The degrading strength and stiffness hysteretic behavior of each wood shear wall in the building can be characterized using an associated numerical model that predicts the walls load-displacement response under general quasistatic cyclic loading. In turn, in this model, the hysteretic behavior of each shear wall is represented by an equivalent nonlinear shear spring element. With this simple approach the response of the building is defined in terms of only three degrees of freedom per floor. This numerical model has been incorporated into the computer program SAWS (seismic analysis of woodframe structures). This paper discusses model formulation. In Part II, the predictive capabilities of this program are compared with recent shake table tests performed on a full-scale two-story woodframe house. CE Database subject headings: Dynamic analysis; Nonlinear analysis; Numerical models; Seismic response; Three-dimensional analysis; Wooden structures; Framed structures.

This is the second of two companion papers on the seismic analysis of woodframe structures. In Part I, a simple numerical model was formulated to predict the dynamic characteristics, quasistatic pushover, and seismic response of woodframe buildings. This numerical model has been incorporated into the computer program SAWS (seismic analysis of woodframe structures). Here in Part II, attention turns to implementation and verification of the SAWS model. To this end, the predictive capabilities of the SAWS program are compared with experimental results obtained from recent shake table tests performed on a full-scale two-story woodframe house under the CUREE-Caltech Woodframe Project. It is shown that the SAWS computer program provides reasonably accurate estimates of the dynamic characteristics, quasistatic pushover, and seismic response of the test structure. Furthermore, the SAWS program requires a minimum amount of data input and provides a fast computational turnaround time in which to analyze a given structure. As a result, this simple numerical may be a useful structural analysis tool for practicing engineers and researchers involved in the seismic design and/or analysis of woodframe structures. CE Database subject headings: Dynamic analysis; Nonlinear analysis; Numerical models; Seismic response; Three-dimensional analysis; Wooden structures; Framed structures; Model verification.

In this paper we investigate experimentally the dynamic interaction between components of electrical substation equipment interconnected by flexible (cable) conductors. Shake table tests were conducted on five different pairs of generic substation equipment specimens interconnected by three different flexible conductors with three different levels of slackness. No damage to any of the three flexible conductors was observed during any of the seismic tests conducted. Two different types of dynamic response were observed during the seismic tests. The first type involves low interaction between the interconnected equipment due to a large slack and/or low intensity ground motion. For this case, very different frequency contents among the relative displacement, absolute acceleration, and force response of each piece of equipment were observed. Also, large horizontal movement of the more flexible equipment was transferred almost entirely into vertical motion of the conductor with little transmission to the more rigid equipment. The second type of dynamic response involves high interaction between interconnected equipment due to a small slack and/or high intensity ground motion. For this case, large vertical acceleration pulses were observed at midspan of the conductor. CE Database subject headings: Connections; Dynamic tests; Earthquakes; Electrical equipment; Seismic effects; Shake table tests.

This paper presents a simple and useful method to estimate the expected displacement at the interconnection point of substation equipment under seismic excitation. Analysis and a survey of qualification reports on standalone equipment revealed that for many types of equipment, the displacement is composed almost entirely of the contribution of the first vibration mode. The generalized single-degree-of-freedom method is therefore recommended to evaluate the displacement, using the first modal-participation factor and the spectral displacement from the required response spectrum. Mean and bound values of this factor were determined and are presented. Shake table tests were performed to investigate the effect of the flexible connection on this factor. It was found that, when sufficient slack is provided, its main effect, on average, is to decrease the standalone modal-participation factor. Index Terms--Dynamics, earthquakes, finite element methods, flexible structures, interconnections, substations.

A two-story, single-family woodframe house, designed according to current engineered code seismic design requirements, was tested on a uniaxial shake table. The main objectives of this experimental study were to determine the dynamic characteristics and the seismic performance of the test structure under various base input intensities representative of both ordinary and near-field ground motions in southern California. The structure was tested with and without interior (gypsum wall board) and exterior (stucco) wall finish materials. The test results revealed good performance of the engineered woodframe structure. Wall finish materials are usually considered in design as nonstructural elements. However, the structure incorporating wall finish materials exhibited a substantial increase in its lateral stiffness and a dramatic reduction in its seismic displacement response. Furthermore, the seismic acceleration response of the structure was only moderately increased by the presence of wall finish materials. These shake table test results provide the motivation for further studies on the evaluation of the long-term effectiveness of wall finish materials as potential structural components of lateral load-resisting systems of woodframe structures. DOI: 10.1061/(ASCE)0733-9445(2002)128:10(1.337) CE Database keywords: Seismic tests; Gypsum; Wooden structures; Buildings, multistory; Construction materials.