scholarly journals Reassessing the Plastic Hinge Model for Energy Dissipation of Axially Loaded Columns

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
R. M. Korol ◽  
K. S. Sivakumaran

This paper investigates the energy dissipation potential of axially loaded columns and evaluates the use of a plastic hinge model for analysis of hi-rise building column collapse under extreme loading conditions. The experimental program considered seven axially loaded H-shaped extruded aluminum structural section columns having slenderness ratios that would be typical of floor-to-ceiling heights in buildings. All seven test specimens initially experienced minor-axis overall buckling followed by formation of a plastic hinge at the mid-height region, leading to local buckling of the flanges on the compression side of the plastic hinge, and eventual folding of the compression flanges. The experimental energy absorption, based on load-displacement relations, was compared to the energy estimates based on section plastic moment resistance based on measured yield stress and based on measured hinge rotations. It was found that the theoretical plastic hinge model underestimates a column’s actual ability to absorb energy by a factor in the range of 3 to 4 below that obtained from tests. It was also noted that the realizable hinge rotation is less than 180°. The above observations are based, of course, on actual columns being able to sustain high tensile strains at hinge locations without fracturing.

2010 ◽  
Vol 163-167 ◽  
pp. 778-789
Author(s):  
Yan Wang ◽  
Shuang Feng ◽  
Xiang Gao

8 plate-reinforced connections are manufactured at 1/2 scale and then tested under low-cyclic loadings to study their hysteretic behavior, and numerical simultation with ANSYS are applied based on the experimental results. Failure patterns, energy dissipation, hysteretic behavior and skeleton curves are comparatively studied by changing the dimensions of the reinforced plates. Results show:(1)the plastic hinge be formed 1/3-1/4 beam depth from the end of reinforced plate and is obvious, there are serious local buckling in the flange and web, and there is no fracture in the beam-to-column welding;(2)The geometric parameters of reinforced plate have important effect to the bearing capacity and ductility of connections. With the increase of length and thickness of reinforced plate, the bearing capacity increases and hysteretic behavior and ductility factor decreases;(3)When the length of reinforced plate is bigger than the design requirements, there is brittle failure in the panel zone, which lead to decrease of capacity of energy dissipation and equivalent viscous damp coefficient;(4)Recommended parameter scope: the recommended length of reinforced plate(flange-plate and cover-plate) is defined as 0.5-0.8 times beam depth, the recommended thickness of flange-plate is 1.2-1.4 times flange and the recommended thickness of cover-plate is 0.7-1.2 times flange.


Author(s):  
Ramakrishnan Maruthayappan ◽  
Hamid M. Lankarani

Abstract The behavior of structures under the impact or crash situations demands an efficient modeling of the system for its behavior to be predicted close to practical situations. The various formulations that are possible to model such systems are spring mass models, finite element models and plastic hinge models. Of these three techniques, the plastic hinge theory offers a more accurate model compared to the spring mass formulation and is much simpler than the finite element models. Therefore, it is desired to model the structure using plastic hinges and to use a computational program to predict the behavior of structures. In this paper, the behavior of some simple structures, ranging from an elementary cantilever beam to a torque box are predicted. It is also shown that the plastic hinge theory is a reliable method by comparing the results obtained from a plastic hinge model of an aviation seat structure with that obtained from a finite element model.


2019 ◽  
Vol 24 (3) ◽  
pp. 04018124 ◽  
Author(s):  
Zhen Wang ◽  
Jingquan Wang ◽  
Yuchuan Tang ◽  
Yufeng Gao ◽  
Jian Zhang

2011 ◽  
Vol 94-96 ◽  
pp. 668-673
Author(s):  
Yan Wang ◽  
Li Ya Zhang ◽  
Shuang Feng ◽  
Xiang Gao

14 models of plate-reinforced connections are analyzed by finite element software ANSYS. Failure mode, hysteretic behavior, ductility and energy dissipation capacity are comparatively studied. Results show that plastic hinge formed at the end of the reinforced plate, hysteretic cruves are full and the connections have good ductility. With the increase in length and thickness of the reinforced plate, bearing capacity increases while hysteretic behavior and ductility factor decrease. If the reinforced plate is longer than the length that design requires, brittle failure occurs in the panel zone. The recommended length of the reinforced plate is defined as 0.5-0.8 times of beam depth, the thickness of flange-plate is 1.2-1.4 times of flange thickness and the thickness of cover-plate is 0.7-1.2 times of flange thickness.


2016 ◽  
Vol 713 ◽  
pp. 66-69
Author(s):  
Walter Costin ◽  
Olivier Lavigne ◽  
Andrei G. Kotousov

This paper focuses on the application of miniaturized fracture tests to evaluate the fracture and hydrogen assisted cracking (HAC) resistance of a selected microstructural constituent (acicular ferrite, AF) which only occurs in microscopic material volumes. Site-specific Focused Ion Beam (FIB) micro-machining was used to fabricate sharply notched micro-cantilevers into a region fully constituting of AF. The micro-cantilevers were subsequently tested under uncharged and hydrogen charged conditions with a nanoindenter. The load displacement curves were recorded and analysed with a simplified plastic hinge model for the uncharged specimen, as AF demonstrated an essentially ductile behaviour. The simplified model assisted with FE simulations provided values of the critical plastic crack tip opening displacement (CTOD). A value of the conditional fracture toughness was thereby determined as 12.1 MPa m1/2. With LEFM, a threshold stress intensity factor, Kth, to initiate hydrogen crack propagation in AF was found to range between 1.56 MPa m1/2 and 4.36 MPa m1/2. All these values were significantly below the corresponding values reported for various ferrous alloys in standard macro-tests. This finding indicates that the fracture and HAC resistance at the micro-scale could be very different than at the macro-scale as not all fracture toughening mechanisms may be activated at this scale level.


Author(s):  
Pedro Silva Delgado ◽  
António Arêde ◽  
Nelson Vila Pouca ◽  
Aníbal Costa

The main purpose of this chapter is to present numerical methodologies with different complexities in order to simulate the seismic response of bridges and then use the results for the safety assessment with one probabilistic approach. The numerical simulations are carried out using three different methodologies: (i) plastic hinge model, (ii) fiber model and (iii) damage model. Seismic response of bridges is based on a simplified plane model, with easy practical application and involving reduced calculation efforts while maintaining adequate accuracy. The evaluation of seismic vulnerability is carried out through the failure probability quantification involving a non-linear transformation of the seismic action in its structural effects. The applicability of the proposed methodologies is then illustrated in the seismic analysis of two reinforced concrete bridges, involving a series of experimental tests and numerical analysis, providing an excellent set of results for comparison and global calibration.


Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2716 ◽  
Author(s):  
Shiming Liu ◽  
Xinxin Ding ◽  
Xiaoke Li ◽  
Yongjian Liu ◽  
Shunbo Zhao

This paper studies the effect of high-strength steel fiber reinforced concrete (SFRC) on the axial compression behavior of rectangular-sectional SFRC-filled steel tube columns. The purpose is to improve the integrated bearing capacity of these composite columns. Nine rectangular-sectional SFRC-filled steel tube columns and one normal concrete-filled steel tube column were designed and tested under axial loading to failure. The compressive strength of concrete, the volume fraction of steel fiber, the type of internal longitudinal stiffener and the spacing of circular holes in perfobond rib were considered as the main parameters. The failure modes, axial load-deformation curves, energy dissipation capacity, axial bearing capacity, and ductility index are presented. The results identified that steel fiber delayed the local buckling of steel tube and increased the ductility and energy dissipation capacity of the columns when the volume fraction of steel fiber was not less than 0.8%. The longitudinal internal stiffening ribs and their type changed the failure modes of the local buckling of steel tube, and perfobond ribs increased the ductility and energy dissipation capacity to some degree. The compressive strength of SFRC failed to change the failure modes, but had a significant impact on the energy dissipation capacity, bearing capacity, and ductility. The predictive formulas for the bearing capacity and ductility index of rectangular-sectional SFRC-filled steel tube columns are proposed to be used in engineering practice.


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