Showing papers on "Earthquake resistant structures published in 1981"

Seismic Damage in Reinforced Concrete Frames

Abstract: Seismic damage in reinforced concrete frames is predicted by analytical methods. Analytical models are developed which can reproduce the behavior of reinforced concrete members under cyclic loads. Accuracy of the analytical models is checked by considering a set of quasi-static cyclic load tests, and the models are found to be sufficiently accurate. Several damage indicators such as ductility, flexural damage ratio, dissipated energy, and cumulative plastic rotation are investigated for each experiment. Based on the test results and physical grounds, flexural damage ratio and dissipated energy are chosen as damage state parameters. The results of the present study are later used to develop a probabilistic model of member failure in reinforced concrete structures.

Earthquake engineering of large underground structures

Abstract: This study identifies and evaluates the current state of the art of earthquake engineering of transportation tunnels and other large underground structures. A review of the past performance of 127 underground openings during earthquakes indicates that underground structures in general are less severely affected than surface structures at the same geographic location. However, some severe damage, including collapse, has been reported. Stability of tunnels during seismic motion is affected by peak ground motion parameters, earthquake duration, type of support, ground conditions, and in situ stresses. The literature on the nature of underground seismic motion is reviewed in detail. Although recorded underground motions tend to substantiate the idea that motion does reduce with depth, amplification at depth has been observed. The current procedures used in the seismic design of underground structures vary greatly depending upon the type of structure and the ground conditions. Procedures for subaqueous tunnels are fairly well formulated; however, procedures for structures in soil and rock are not as well formulated. Numerical procedures to predict dynamic stresses are not completely compatible with current static design procedures, which are more strongly affected by empirical methods than by stress-prediction models. Recommended research activities include the systematic reconnaissance of underground structures following major earthquakes, the placement of instrumentation for recording seismic motion in tunnels, analytical studies of underground motion, and the further development of seismic design procedures for structures in soil and rock. (Author)

Theory and application of experimental model analysis in earthquake engineering

Abstract: The feasibility and limitations of small-scale model studies in earthquake engineering and practice are summarized. Emphasis is placed on dynamic modeling theory; a study of the mechanical properties of model materials; the development of model construction techniques; and an evaluation of the accuracy of prototype response prediction through model case studies on components and simple structures. The basics of similitude theory and its application to the modeling of dynamically excited structures are reviewed and similitude laws for various types of models are developed. Materials for modeling of steel and reinforced concrete structures are examined with regard to cyclic load effects. Systematic material testing procedures are developed for the investigation of alternative model materials. Also, problems encountered in the construction of models are identified and recommendations are suggested to correct them. The research demonstrates that model analysis can be used in many cases to obtain quantitative information on the seismic behavior of complex structures which cannot be analyzed confidently by conventional techniques.

The Structural Fuse: An Inelastic Approach to Earthquake-Resistant Design of Buildings

Abstract: An alternative to the empirical approach to earthquake-resistant design of buildings is proposed and illustrated with a design example. Instead of strengthening every member to resist deformation under earthquake loads, the suggested approach deliberately makes some members, mostly beams, weaker, so that they will yield in a controlled fashion during an earthquake. Yielding beams dissipate energy, reducing stress on the more crucial columns and walls. Carefully selected earthquake accelerograms are used as loading, and dynamic inelastic response history analysis is used to determine member forces and deformations.

Principles of tunnel design for seismic regions

Abstract: The paper deals with the basic design principles for underground structures that are to be located in seismic regions. Design methods are described for certain types of linings for single tunnels and for a complex of parallel structures. A method is given for determining the minimum earthquakeproof distance between parallel tunnels. The methods are illustrated by examples. (A) (TRRL)

Mitigation of earthquake damage on eastern highway systems

Abstract: This article reviews highway bridge damage caused by a major earthquake in the Eastern United States. Past earthquake-induced failures to the highway network are reviewed to show the vulnerable components of the highway system. Major obstructions in the implementation of existing technology in the United States is discussed along with research recommended to improve earthquake-resistant highway bridge design and construction.