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.

Evaluation of Seismic Performance for Tunnel Retrofit Project

Abstract: A seismic retrofit program at Yerba Buena Island Tunnel is presented as a case history. The studies include evaluations of portal stability under earthquake excitation and performance of the tunnel liner as a result of seismic induced deformation. Due to different potential failure modes at the two portal areas, two separate evaluation techniques were utilized. Key block theory in conjunction with a Newmark type analysis was used to assess movements of a potential failure wedge at the west portal slope, while discontinuous deformation analysis was utilized at the east portal slope to evaluate a rotational mode of failure. To assess the performance of the liner subjected to design earthquakes, a two-step analysis procedure was adopted. The first step was to compute seismic induced deformations of the tunnel subjected to seismic wave propagation through the island rock without the presence of the liner. The second step, not reported in this paper, involved imposing the deformations of the tunnel onto the structural liner through spring elements that accounted for interaction between the liner and the surrounding rock. From the studies, performance of the existing tunnel supports was found to be acceptable.

Property modification factors for seismically isolated bridges

Abstract: An analytical study investigating how changes in the mechanical properties of individual seismic isolators affect the response of isolated bridge structures subjected to earthquake excitation is summarized Nonlinear response-history analyses are conducted utilizing bins of recorded earthquake ground motion pairs Twenty bilinear isolation systems are considered so that the results of this study are broadly applicable to the design of seismic isolation systems in the United States Variations in the mechanical properties are considered using a property modification factor, λ , to modify the appropriate bilinear isolator parameter The results of analyses considering nominal and modified isolation systems are used to systematically identify changes in system response as a function of the property modification factor These results are used to determine threshold values of the property modification factor that should aid engineers in the preliminary design and assessment of an isolation system prior to perf

Structural control technology: system identification and control of flexible structures

Abstract: The main trend in structural technology is to change from conventional earthquake resistant structures, which are designed 'not to collapse even under the strongest earthquake' to structural controlled buildings, which are designed 'to suppress the vibrations itself'. Indications are that control methods will be able to make a genuine contribution to this problem area, which is of great economic and social importance. Current researches in the field of active structural control focus on: system identification, model order reduction, limited control authority, available measurements etc. The article reviews some of the developments in the area of controlled civil structures and highlights a robust control perspective in active vibration suppression control of flexible structures, considering a grey box approach in the system identification process.

Displacement-based assessment of reinforced concrete frames in earthquakes

Abstract: In this paper, a displacement-based approach to evaluating detailing requirements for frame elements is presented. Expressions are derived for the participation of beams, columns, joints and anchorages in overall story drift. Simple element models are presented for beam-column joints and anchorages, and guidelines for conventional sectional analysis of beams and columns are given. With an assessment of the local demand in each element type and mechanical models of element behavior, it is demonstrated that member variables normally considered as part of detailing can be accounted for in a quantitative supply-versus-demand fashion. A case study is made for an example in the ACI Committee 352. Recommendations to illustrate how a displacement-based frame evaluation is carried out and to provide a reference point for comparison with an existing design approach for beam-column joints.