Papers by Keyword: Plastic Hinge

Abstract: Aim of this paper is the evaluation of the increasing of the load-carrying capacity of masonry arches strengthened at intrados extrados with poliparafenilenbenzobisoxazole (PBO) fabric reinforced cementitious mortar composite. An analytical procedure is proposed, in the Limit Analysis context, considering two schemes of load: a vertical load applied at the crown of the arch and a horizontal distribution proportional to the weight. The presence of the composite material is introduced by considering a plastic behaviour of the hinges defining the virtual kinematic mechanism compatible with the Limit Analysis hypotheses. Two assumptions on these mechanisms are made: a correct position of the hinges inside the cross-section of the masonry arch or a simplified location at the intrados or at the extrados of the structure. Finally, a parametric survey is carried out in order to understand the influence of the involved parameters on the load-carrying capacity of the strengthened masonry arches.

Abstract: In reinforced concrete buildings in case of a possible earthquake, the buildings slamp as they lost their horizontal stability because of hinging of column ends. The assumptions for plastic hinge lengths are present during project stage of reinforced concrete buildings. According to Turkish Earthquake Regulations, although plastic hinge length is determined to be 0.5h, it's known that plastic hinge length is determined via various formulas in some other regulations all over the world. In reinforced concrete columns, it's necessary to indicate the effect of plastic hinge length on the column behavior. For this purpose, pushover analysis of 5 column samples having different plastic hinge lengths was performed with non-linear analysis program. As a result of pushover analysis, situations of plastic hinges formed in columns and their load-displacement curves were determined. The graphs and the data were compared and the results were discussed.

Abstract: This paper analyzed the mechanical properties of the web opening nodes on the steel frame which considered the combined effects, with the finite element analysis software ABAQUS . When the structure with the web openings withstood static loads,formation process of plastic hinge was also analyzed. By applying a load-displacement curve at the endpoint of the main beam, the impact of the flange thickness ratio on the seismic performance was researched. The results showed that reducing the flange thickness will decrease the structural capacity, while the improvement of hysteretic performance was not significant. However, reducing the flange thickness and increasing width of the flange at the same time would not only increase the structural capacity, but also improve the hysteretic behavior and the seismic performance of the structure.

Abstract: Buckling-Restrained Brace (BRB) in China, Taiwan, and Japan, as a kind of hysteretic damper has been installed into steel frame structure; In the United States, however, it has been installed into the hinge-connected steel framework, as the main seismic element in order to add lateral stiffness and strength.This paper according to the design codes of frame structure in China, Japan and the United States,establishes the research model based 0n the typical steel frame form of China, Japan, and the US.The main research parameters of the model are horizontal force sharing ratio of BRB (β) and frame strength of BRB (CB)。Through the steel consumption,the relationship of story drift and story shear, the formation of plastic hinge of the design model,it compares the steel frame seismic design method of China, Japan and the United States.The steel consumption of frame is related to the strength of the frame, but has nothing to do with the frame structure form;The plastic hinge of each model focused mainly on the BRB,reflecting the overall mechanism; As to seismic design requirements, the Japanese codes are stricter, codes of China and the United States is relatively close.

Abstract: This paper presents a comparative analytical study on seismic response of low rise three storeys concrete frame reinforced with super-elastic material as rebar elements. The super-elastic shape memory alloy rebars were used as reinforcement in two plastic hinge zones of the frame, beam plastic hinge zones and column plastic hinge zones. The response of the frame structure with two different reinforced cases is compared to response of the frame structure reinforced with regular steel material. Nonlinear dynamic time history analysis is performed in this study. Three different great earthquake ground motions were used to determine the seismic response of the frame structures in terms of frame top displacement time history and inter-storey drift along the frame height for different cases of reinforcements. Results obtained from the analysis show that the seismic response of low rise frame reinforced with super-elastic SMA rebars is affected by the zone of which SMA rebar are used in reinforcement. The SMA column reinforcement is more effective than SMA beam reinforcement in reducing the frame response.

Abstract: The main objectives of this paper was to investigate the cyclic performance of splice connection in weak-axis column-tree connections with the formation of plastic hinge assumed at splice connection and provide some design recommendations. By reducing the cross-sectional area of the splice plates, the splice connection in this test are designed as a weaken component to utilize the ductility capacity and energy dissipation. The results showed that it could develop the plastic rotation capacity in the beam splice connection and portion in the link beam but not increase the energy dissipation capacity during the same story drift ratio.

Abstract: Friction Pendulum Systems have been used as base isolation systems for both new construction and retrofit around the world. This paper presented its implementation in an office building located in Shanghai. To evaluate its impact on seismic performance of the retrofitted structure, models are needed to capture the intricate nonlinear behavior of both structural components and isolator elements. Nonlinear time history analysis of the building for the original and retrofitted cases was conducted to assess the efficiency of the isolation system at the high earthquake level. The numerical results indicate that the retrofitted structure experiences significantly less damage and less deformation due to the shake isolation and energy dissipation through the isolators.

Abstract: In collapse-resistant design of a structure under accidental local action, it is important to understand the failure mechanism and alternative load paths. In this paper, a pseudo-static experimental method is proposed. Based on which, the collapse of frame structure was simulated with testing a 1/3 scale; 4-bay and 3-story plane reinforced concrete frame. In the experience, the middle column of the bottom floor was replaced by mechanical jacks to simulate its failure, and the simulated superstructure’s gravity load acted on the column of the top floor by adopting a servo-hydraulic actuator with force –controlled mode.

Abstract: Moment resistant steel connections are widely used in steel structures and play a significant role in reliability of structures, especially in earthquake-prone regions. After the Northridge earthquake, the invention of Reduced Beam Section (RBS) connections was a turning point in the design of the moment-resistant steel connections. In the present study, the seismic behavior of the RBS connections with reduced flange width as well as the AW-RBS connections with reduced web section in the double section beams are investigated. The results of a numerical study conducted using ABQUS finite element modeling software to investigate the ductility, energy absorption and plastic behavior of the RBS joints under cyclic loads are presented. Results showed promising performance with regards to energy absorbance and ductility for the AW-RBS connections.

Abstract: Under the influence of floor, the reinforced concrete frames have never realized the yield mechanism of strong column and weak beam which is a seismic design principle. To study the influence of realizing such yield mechanism because of floor with opening, its necessary to establish two frame models that one is with common floor and the other is floor with opening around the joints whose size is 600mm×600mm by the ANSYS that is finite element software. Moreover, these models apply the seismic loads and carry out the time history analysis. The results show that the frames stiffness has been weakened after the floor is opened, the peak acceleration reduced and the displacement increased. However, the ductility has been strengthened, which slightly reduce the reaction of the acceleration and displacement. In addition, the appearance of the plastic hinges in the beam are advanced, and the development of their plastic deformation becomes quicker than those of columns, and the plastic hinges in the bottom of the column are delayed. Therefore, the measure of opening the floor can realize the ideal yield mechanism of strong column and weak beam to reach the seismic target that the building cant collapse under the strong shocking.