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Plastic Hinge (plastic + hinge)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

Development and validation of a metallic haunch seismic retrofit solution for existing under-designed RC frame buildings

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 14 2006
Stefano Pampanin
Abstract The feasibility and efficiency of a seismic retrofit solution for existing reinforced concrete frame systems, designed before the introduction of modern seismic-oriented design codes in the mid 1970s, is conceptually presented and experimentally investigated. A diagonal metallic haunch system is introduced at the beam,column connections to protect the joint panel zone from extensive damage and brittle shear mechanisms, while inverting the hierarchy of strength within the beam,column subassemblies and forming a plastic hinge in the beam. A complete step-by-step design procedure is suggested for the proposed retrofit strategy to achieve the desired reversal of strength hierarchy. Analytical formulations of the internal force flow at the beam,column-joint level are derived for the retrofitted joints. The study is particularly focused on exterior beam,column joints, since it is recognized that they are the most vulnerable, due to their lack of a reliable joint shear transfer mechanism. Results from an experimental program carried out to validate the concept and the design procedure are also presented. The program consisted of quasi-static cyclic tests on four exterior, , scaled, beam,column joint subassemblies, typical of pre-1970 construction practice using plain round bars with end-hooks, with limited joint transverse reinforcement and detailed without capacity design considerations. The first (control specimen) emulated the as-built connection while the three others incorporated the proposed retrofitted configurations. The experimental results demonstrated the effectiveness of the proposed solution for upgrading non-seismically designed RC frames and also confirmed the applicability of the proposed design procedure and of the analytical derivations. Copyright © 2006 John Wiley & Sons, Ltd. [source]

The transfer matrix method applied to steel sheet pile walls

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2003
D. A. Kort
Abstract This paper proposes two subgrade reaction models for the analysis of steel sheet pile walls based on the transfer matrix method. In the first model a plastic hinge is generated when the maximum moment in the retaining structure is exceeded. The second model deals with a beam with an asymmetrical cross-section that can bend in two directions. In the first part of this paper the transfer matrix method is explained on the basis of a simple example. Further the development of two computer models is described: Plaswall and Skewwall. The second part of this paper deals with an application of both models. In the application of Plaswall the effect of four current earth pressure theories to the subgrade reaction method is compared to a finite element calculation. It is shown that the earth pressure theory is of major importance on the calculation result of a sheet pile wall both with and without a plastic hinge. In the application of Skewwall the effectiveness of structural measures to reduce oblique bending is investigated. The results are compared to a 3D finite element calculation. It is shown that with simple structural measures the loss of structural resistance due to oblique bending can be reduced. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Cyclic tests of post-tensioned precast CFT segmental bridge columns with unbonded strands

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2006
Chung-Che Chou
Abstract Two ungrouted post-tensioned, precast concrete-filled tube (CFT) segmental bridge columns were tested under lateral cyclic loading to evaluate the seismic performance of the column details. The specimens included a load stub, four equal-height circular CFT segments, and a footing. Strands were placed through the column and post-tensioned to provide a precompression of the column against the footing. One specimen also contained energy-dissipating devices at the base to increase the hysteretic energy. The test results showed that (1) both specimens could develop the maximum flexural strength at the design drift and achieve 6% drift with small strength degradation and residual displacement, (2) the proposed energy-dissipating device could increase energy dissipation in the hysteresis loops, and (3) the CFT segmental columns rotated not only about the base but also about the interface above the bottom segment. This study proposed and verified a method to estimate the experimental flexural displacement using two plastic hinges in the segmental column. Copyright © 2005 John Wiley & Sons, Ltd. [source]