Dynamics of structures

Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the “efficiency” and “sufficiency” of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions.

Structure-specific scalar intensity measures for near source and ordinary earthquake ground motions

Chapter 1. Introduction Chapter 2. Structural Steel Chapter 3. Plastic Behavior at the Cross-Section Level Chapter 4. Concepts of Plastic Analysis Chapter 5. Systematic Methods of Plastic Analysis Chapter 6. Applications of Plastic Analysis Chapter 7. Building Code Seismic Design Philosophy Chapter 8. Design of Ductile Moment-Resisting Frames Chapter 9. Design of Ductile Concentrically Braced Frames Chapter 10. Design of Ductile Eccentrically Braced Frames Chapter 11. Design of Ductile Buckling-Restrained Braced Frames Chapter 12. Design of Ductile Steel Plate Shear Walls Chapter 13. Other Ductile Steel Energy Dissipating Systems Chapter 14. Stability and Rotation Capacity of Steel Beams Index

Ductile design of steel structures

The seismic performance of a posttensioned energy dissipating (PTED) connection for steel frames is investigated analytically and experimentally. The PTED connection incorporates posttensioned high-strength bars to provide a self-centering response along with energy dissipating bars that are able to yield in axial tension and compression. The analytical study involves the development of an equivalent iterative sectional analysis procedure to predict the moment-rotation relationship of the PTED connection. Based on this analytical model, a simple design procedure for PTED connections is described. In the experimental study, a cyclic component test was performed on two energy dissipating bars and a cyclic test was conducted on a large-scale exterior beam-to-column PTED connection. The results of the tests show that the PTED test specimen was able to undergo large inelastic deformations without any damage in the beam or column and without residual drift. The proposed analytical model and design procedure wer...

Posttensioned Energy Dissipating Connections for Moment-Resisting Steel Frames

In this paper, the use of the combined deterministic-stochastic subspace identification algorithm for the experimental modal analysis of mechanical structures is discussed. The algorithm requires artificial forces to be applied to the structure, so it can be used for experimental modal analysis (EMA). The algorithm can also be used for operational modal analysis (OMA), since the excitation level of the artificial force(s) can be low compared to the excitation level of the ambient forces. Both the modes that are artificially excited and those that are excited by the ambient forces are identified. This type of operational modal analysis is called an OMAX analysis (Operational Modal Analysis with eXogenous inputs) [1]. The main advantages of OMAX over OMA are that the modes that are excited by the artificial forces can be scaled to unity modal mass and that a higher number of modes can be identified.

Reference-based combined deterministic-stochastic subspace identification for experimental and operational modal analysis

Shear wall systems are one of the most commonly used lateral-load resisting systems in high-rise buildings. The composite shear wall system studied herein consists of a steel plate shear wall with a reinforced concrete wall attached to one side of it using bolts. In this paper, experimental studies of three-story composite shear wall specimens are presented and test results are discussed. Two half-scale specimens were tested and both showed highly ductile behavior and stable cyclic postyielding performance. The specimens were able to tolerate 33 cycles of shear displacements and reach maximum interstory drift of more than 0.05. Here the interstory drift is defined as lateral movement of the floor over the story height. The bolts connecting the reinforced concrete walls to steel plate shear walls were able to ensure the composite action by bracing the steel plate shear wall to the reinforced concrete shear wall and preventing the overall buckling of steel plates. During late cycles and after shear yielding of the steel plate, inelastic local buckling of the steel plate shear wall occurred in the areas between the bolts. The experimental results and their implication in seismic design are summarized and discussed.

Cyclic Behavior of Traditional and Innovative Composite Shear Walls

Page 1 ACKNOWLEDGMENTS / Page 3 TABLE OF CONTENTS / Page 4 NOTATIONS AND GLOSSARY / Page 5

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Seismic Behavior and Design of Steel Shear Walls

The problems with welded moment connections in the Northridge earthquake of 1994 gave researchers incentive to examine the actual contribution of the simple, or shear, connections to the lateral resistance of welded steel moment-frame buildings With the composite action of the floor slab, these connections may have more lateral resistance than traditionally assumed; thus, they may be used in the repair or retrofit of damaged welded steel moment-frame buildings or used more actively in new construction To evaluate these possibilities, and to establish the strength, stiffness, and ductility of these connections under cyclic loading, two series of eight full-scale, cyclic tests on shear connections with floor slabs were planned The first test series has demonstrated the cyclic behavior of the simple connections and has shown that these “pinned” connections have significant moment capacities, both on their own and with the contribution of the floor slab This paper summarizes the results of the first eight

Cyclic Testing of Simple Connections Including Effects of Slab

Shear tab connections, acting compositely with the floor slab, are capable of providing some lateral resistance in steel frame buildings. This resistance was suspected from the events of the 1994 Northridge Earthquake and verified in a series of tests. For performance evaluation of steel structures, it is necessary to quantify the non-negligible rotational strength and stiffness of these composite connections, a task that cannot be accomplished through the use of simple rules of thumb. Therefore, trends in the moment–rotation behavior of the connections are identified from comparison of the cyclic behavior against parameters such as number of bolts, type of concrete, use of slab reinforcement, and the presence of a column web cavity. Analysis of these trends leads to guidelines for determining parameters for a basic backbone moment–rotation curve. These guidelines depend heavily on applicable limit states for elements of the connections and connection geometry. Predicted values of moment and rotation capa...

Abolhassan Astaneh-Asl

Papers

Cyclic Behavior of Traditional and Innovative Composite Shear Walls

Seismic Behavior and Design of Steel Shear Walls

Cyclic Testing of Simple Connections Including Effects of Slab

Moment–Rotation Parameters for Composite Shear Tab Connections

Hysteresis model of bolted-angle connections