Earthquake resistant structures

About: Earthquake resistant structures is a research topic. Over the lifetime, 1126 publications have been published within this topic receiving 27467 citations.

Experimental Behavior of Dual Steel System

Abstract: A six-story eccentrically chevron-braced dual steel system (EBDS) was subjected to 24 earthquake ground motions with effective peak accelerations of up to 0.55\dg on the earthquake simulator at the University of California at Berkeley. The design, construction, dynamic characteristics and experimental behavior of this eccentrically braced system is discussed in this paper. The EBDS was analyzed for its compliance with current earthquake-resistant regulations that include the 1985 Uniform Building Code (UBC) 1984 Applied Technology Council (ATC) 3–06, and 1986 Structural Engineers Association of California (SEAOC). A substantial overstrength of this dual system with respect to its nominal yielding strength was observed and this is discussed in terms of the response modification factors currently adopted by the ATC and SEAOC. The lateral force distributions for the elastic level tests corresponded to the code-base design lateral force distributions but varied considerably for the collapse level tests. The role of the ductile moment-resisting space frame (DMRSF) in the EBDS is discussed in light of its performance during the testing program. Conclusions are drawn regarding the suitability of the EBDS for regions of high seismic risk and the response modification factors and lateral forces distributions currently used or implied in the UBC, ATC, and SEAOC.

Seismic Retrofit of Bridge Joints in Central U.S. with Carbon Fiber-Reinforced Polymer Composites

Abstract: The objectives of this study were 1) to investigate failure modes of reinforced concrete bridge beam-column subassemblies under seismic loads; and 2) to propose an economic and efficient retrofit scheme using composites. To fulfill these objectives, two test units, designated as Units 1 and 2, were retrofitted and tested. Unit 1 was retrofitted at different damage levels and Unit 2 was strengthened in its virgin condition according to nearly the same retrofit scheme. Test results indicate that the repair and retrofit schemes employed in the damaged or undamaged columns were equally efficient in preventing shear failure of the column. On the other hand, whereas repairing the damaged beam-column joint in Unit 1 was inefficient, retrofitting the undamaged joint of Unit 2 was successful. An analytical model was also developed to include the contribution of joint flexibility into the lateral response of the units. Test results along with the recommended procedures for seismic design and implementation of the retrofit schemes are presented and discussed in this paper.

Soil-Structure Interaction Effects on Seismic Response of multi-story Buildings on Raft Foundation

Abstract: The investigation on the energy transfer mechanism from soils to buildings during earthquakes is critical for the design of earthquake resistant structures and for upgrading existing structures. Thus the need for research into Soil-Structure Interaction (SSI) problems is greater than ever. Moreover, recent studies show that the effects of SSI may be detrimental to the seismic response of structure and neglecting SSI in analysis may lead to un-conservative design. Despite this, the conventional design procedure usually involves assumption of fixity at the base of foundation neglecting the flexibility of the foundation, the compressibility of soil mass and consequently the effect of foundation settlement on further redistribution of bending moment and shear force demands. Hence the soil-structure interaction analysis of multi-story buildings is the main focus of this study; the effects of SSI are analyzed for typical multi-story building resting on raft foundation. Three methods of analysis are used for seismic demands evaluation of the target moment resistant frame buildings: equivalent static load (ESL); response spectrum (RS) methods and nonlinear time history (TH) analysis with suit of nine time history records. Three-dimensional FEM model is constructed to analyze the effects of different soil conditions and number of stories on the vibration characteristics and seismic response demands of building structures. Numerical results obtained using soil structure interaction model conditions are compared to those corresponding to fixed-base support conditions. The peak responses of story shear, story moment, story displacement, story drift, moments at beam ends, as well as force of inner columns are analyzed. The analysis results of different approaches are used to evaluate the advantages, limitations, and ease of application of each approach for seismic analysis.

The Mexico Earthquakes-1985: Factors Involved and Lessons Learned

Abstract: This publication reports initial results of study of the 1985 Mexico earthquake, one year after the event. The findings present sufficient depth of analysis to provide an understanding of the causes and effects of earthshaking within Mexico City that resulted in extensive damage to some buildings and structures. Also reported are the assessment of damage caused by the earthquake and emergency response including recovery operations. Buildings of different construction types and materials were subject to the earthquake. Performance of their response is analyzed and evaluated. Topics presented include seismicity associated with the Mexico earthquake of 1985. General engineering topics include dynamic soil response, foundation failure, performance of structures and analysis of building failure, analysis of lifelines performance, and emergency response including building code regulations. Specific practical problems addressed include: modeling of soil motion, modeling of structural behavior, analysis of drift in frame structures, structural pounding, structural stiffness softening due to long duration motion, soil-structure interaction, influence of local soil conditions on building performance, dam behavior, and repair and strengthening of buildings.