Showing papers on "Earthquake resistant structures published in 1982"

Response of friction damped braced frames

Abstract: A new concept of aseismic design for steel framed buildings is proposed. By providing sliding friction devices in the bracing system of the framed buildings, their earthquake resistance and damage control potential can be considerably enhanced. During severe earthquake excitations, the friction device slips and a large portion of the vibrational energy is dissipated mechanically in friction rather than inelastic yielding of the main structural components. Results of inelastic time-history dynamic analysis show superior performance of the friction damped braced steel frames when compared to computed responses of other structural framing systems. The proposed friction devices act, in affect, both as safety valves and structural dampers. The device may also be conveniently incorporated in existing framed buildings to upgrade their earthquake resistance.

Behavior of Reinforced Concrete Lapped Splices for Inelastic Cyclic Loading

Abstract: The behavior of lapped splices in reinforced concrete is described based on over 60 large beam and column-type specimens subjected to high-level repeated or reversed cyclic flexural loads. Splices were located both in the corners and interior of the specimens. Main variables were transverse steel requirement, load history, magnitude of shear, and splice length. A minimum of fifteen reversing load cycles beyond yield was considered indicative of satisfactory performance. A companion paper contains suggested design specifications.

Seismic reliability of lifeline networks

Abstract: An efficient method for seismic reliability assessment of lifeline networks, such as water distribution systems and communication or transportation networks, is developed. Lifeline component failures resulting from ground shaking and fault differential movements are analyzed using structural performance functions given in terms of earthquake variables. An improved fault-rupture model which considers the ruptured area produced by an earthquake on the fault plane is utilized. A new, polynomially bounded method for computer lifeline network reliability is developed. It is shown that for a fixed earthquake magnitude on a fault, the network will take on at most 2 n stages where n is the number of network components. Computing the seismic reliability of large networks becomes feasible using these new techniques. A water distribution system is analyzed using newly developed computer programs.

Eccentric Bracing in Tall Buildings

Abstract: Primary concerns in the design of high-rise buildings, particularly those located in seismically active regions, are the control of interstory drift and the ability of the structure to withstand inelastic deformations. The design of the 47 story 4 Embarcadero Center building in San Francisco, California, utilizes a recently developed structural system that provides economical control of interstory drift, as well as sufficient ductility to enable the structure to perform satisfactorily in the event of a major earthquake. The use of eccentric bracing elements is the key to this structural system. This paper describes how an eccentric bracing scheme was used to satisfy the requirements for both drift control and ductility in the design of a high-rise structure located in a zone of high seismic exposure.

Application of modern control theory for building structures

Abstract: Active control systems can be used to reduce the effect of strong-motion earthquakes. During the past two decades, various approaches have been applied to find the optimal control law. A technique based upon modal analysis is developed and presented herein. The present method is based upon a stochastic approach and a modal analysis for reducing displacement response of building structures to earthquakes. For the purposes of illustration, a numerical example is also given.

Static and Dynamic Testing of Model Precast Concrete Shearwalls of Large Panel Buildings

Abstract: This paper presents a methodology for designing, fabricating, and testing small-scale dynamic models of precast concrete shearwalls originating in the construction of large panel precast concrete buildings. Design and construction of a set of 3/32-scale models which satisfy dynamic similitude is presented. Resonent vibration testing of three-story and five-story precast concrete shearwall models on a small shake table is described. Additional monotonic and cyclic tests on six five-story shearwall models under simulated earthquake loading are presented. The main parameters in these tests were the amount of steel in the vertical ties and cyclic versus monotonic loading. (A) For the covering abstract see IRRD 853656.