Showing 4 results for Ductility
F. Nateghi-A and N.a. Hosseinzadeh,
Volume 20, Issue 2 (4-2001)
Abstract
This paper presents a methodology for the assessment of ductility and strength capacities in low-rise buildings. This method utilizes the characteristics of force-displacement for the lowest story level or considers the weakest story in any given low-rise building for its primary analysis. Calculations are based on two levels of earthquake motions, namely strong earthquakes (PGA=0.3 g), and very strong earthquakes (PGA=0.45). Failure mechanism for the structure is established based on three criteria which are: a) bending mode, b) shear mode, and c) shear-bending mode. Evaluation is then performed using a five step procedure starting with a: modeling the building, b) developing the non-linear properties of the model, c) strength calculations, d) ductility calculations, and finally, e) assessing the safety of the building under consideration. All these evaluations are performed based on a matrix format, which simplifies the whole procedure. Developed equations and step-by-step procedure are presented and described in this paper Satisfactory results are obtained from the use of the method developed.
Keywords: Strength, Ductility, Failure mechanism, Low-Rise R. C. Buildings
M. Khan-Mohammadi and M. S. Marefat,
Volume 25, Issue 1 (7-2006)
Abstract
To assess the performance criteria of the reinforced-concrete, five-storey residential buildings common in Iran, an
experimental study in the structural laboratory of the University of Tehran has been conducted. The test program includes cyclic and monotonic load tests of six beams that represent three-to-five storey buildings with rigid frame structures. Using definitions given in FEMA-356 and ATC-40, stages of immediate occupancy, life safety, and collapse prevention have been identified on the drift- force curves of all specimens. Based on the test results, values of the plastic rotation, ductility, strain in concrete cover and in longitudinal bar, crack width, damage index, and length of plastic region at different levels have been determined. It was found that the recommended values of plastic rotation and ductility for reinforced concrete beams by FEMA-356 are conservative. The length of plastic hinge region in the stage of immediate occupancy is about half the plastic hinge length in the stage of life safety and it increases by 20% from life safety to collapse prevention
S. M. Zahrai and B. Rad,
Volume 25, Issue 2 (1-2007)
Abstract
In recent years, destructive earthquakes have shown the deficiencies of the existing buildings. One of the most effective mechanisms for dissipating the earthquake energy is inelastic deformation of the steel components. The objective of this research is to study the application of metallic dampers for dissipation of the earthquake energy and to investigate the behavior of concrete structures incorporating these dampers. Therefore, the metallic dampers and the behavior of concrete structures having these dampers are studied first. Afterwards, a typical metallic damper is used in four different types of concrete structure. The required dampers are designed and nonlinear earthquake analysis is applied to investigate the behavior of the structures. Finally, the buildings are subjected to various earthquakes to generalize the results. The results show that the incorporation of the metallic dampers significantly decreases the relative and absolute drift, the structure and the stories damage indices and, finally, the number of plastic hinges. Furthermore, the hysteretic energy dissipation demand also decreases in structural components. Despite the reduction in the inner forces of structural components, story shear forces slightly increase due to increase of lateral stiffness, but much of these forces will concentrate in dampers. Moreover, the combination of moment resisting frame, shear wall, and metallic dampers are studied. The results show a similar trend in the stated parameters- especially the drift and the hysteresis energy dissipation demand.
M. Sheikhi and H. Haji-Kazemi,
Volume 25, Issue 2 (1-2007)
Abstract
Jacketing of reinforced concrete columns is a common and useful strengthening method. This method substantially improves mechanical properties of the column, such as flexural strength as well as shear and ductility. In this paper, the behavior of confined reinforced concrete columns are investigated. The results indicate that the method is more effective for slender columns in the region of their failure zone.
