نوع مقاله : پژوهشی
نویسندگان
1 گروه مهندسی عمران، دانشگاه آزاد اسلامی واحد سمنان
2 دانشکدهی مهندسی عمران، دانشگاه علم و صنعت ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In a strong earthquake, a standard reinforced concrete column may develop plastic deformations in regions often termed; plastic hinge regions. The formation of a plastic hinge in an RC column; in regions that experience
inelastic action; depends on the characteristics of the earthquake; as well as column details.
Recent earthquakes in Turkey (1999), Taiwan (1999), India (2001), Iran (2003), China (2008) and Japan (2011) have caused considerable loss of life and extensive damage to structures. The damage observed during the recent earthquakes proved the engineers hypothesis that structures located within the near-fault area suffer more severe damage than structures located outside this zone. The near-fault of an earthquake can be defined as the area in the close vicinity of the fault rupture surface. Besides strong shaking, the characteristics of near-fault ground motion are linked to the fault geometry and the orientation of the travelling seismic. Vertical strike-slip faults can produce a directivity effect, and dip-slip faults can produce directivity effects, as well as hanging wall effects.
Although experimental tests of RC members provide valuable information about their behavior, these are normally expensive, time-consuming and require considerable human and physical resources. By using dynamic nonlinear finite element analysis, it is possible, at comparatively lower cost and effort, to predict the response of RC structures and members: e.g. plastic hinge length.
Using the wealth of recent ground motion data, in the present paper, 462 inelastic time-history analyses have been performed to predict the nonlinear behavior of RC columns under near-fault earthquakes having a fling step. The effects of axial load and height over depth ratio, as well as the different characteristics of earthquakes, are evaluated by finite element methods and results are compared with corresponding experimental data.
Analytical models for columns analyzed under high axial loads exhibit longer plastic hinges than those analyzed under low axial loads. Based on the results, a simple expression is proposed that can be used to estimate the plastic hinge length of RC columns subjected to earthquakes. The results also show that potentiall_{p}$specified by ICC is not satisfactory for columns supporting high axial loads, and can even be non-conservative in some cases. It is suggested that the length of the region, in which closely-spaced ties are used, should be increased from 1.0h to 1.5h from the joint face.
کلیدواژهها [English]
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