Papers by Keyword: Beam-Column Joint

Abstract: Beam-column joint is the most vulnerable location of a moment-resisting reinforced concrete frame structure. The joint region experiences the maximum shear stress both in vertically and horizontally which is generated due to the shear transfer mechanism from the adjoining beams and columns. The shear capacity and bond stress capacity are the two major factors affecting the strength of a joint core in RC structure. An important discovery recently is the ductile behaviour of the whole structure under repeated loading. The behaviour of the concrete beyond elastic limit which is in the concrete hardening zone can drastically influence the ductility of the concrete. The non-linear stress-strain behaviour after the onset of the initial crack and up to ultimate compressive strength plays an important role in improving ductility. Beyond the ultimate compressive strength, concrete will undergo softening which is neglected in this study as once concrete reaches ultimate stress it is unsafe for service. This material ductility can be fulfilled with the application of high-strength fibres with ductile behaviour. However, the hybridization of two or more fibres can incorporate two different characteristics of the fibre used. The use of ordinary-grade of concrete moreover reduces the shear-resisting capacity of the joint. A hybrid mix of hooked-end steel fibre with basalt fibre and crimpled steel fibre with polypropylene fibre are used with a volume fraction of 1% to 1.4% of the concrete. In this study, ordinary M25 grade concrete and fibre mixed M25 grade concrete is employed under static and cyclic loading. The laboratory tests are also conducted to evaluate the compressive strength, split-tensile strength, and flexural strength of the hybrid mix fibre-reinforced concrete at the age of 28^th days. Five full-scale models of the beam-column joint are designed as per the Bureau of Indian Standards. Numerical models of concrete and steel reinforcement are developed. Numerical analysis is carried out using finite element software ANSYS-v21. The behaviours of the beam-column joint are observed under static as well as cyclic loading. Crack patterns, first crack load, initial displacement, ultimate load, and ultimate displacement are observed under static conditions. And under cyclic loading, hysteresis load vs displacement, energy dissipation, and stiffness degradation are observed. The hybridization of hooked steel with basalt fibre gives better results in mechanical strengths and the hybrid effect of crimpled steel with polypropylene fibre gives better results in mechanical strengths. And also under numerical study, the above specimens show an improvement in energy dissipation capacity. Keywords beam-column joint, hybrid fibre reinforced concrete, numerical concrete model, ANSYS, static, reverse cyclic, energy dissipation, stiffness, crack

Abstract: In New Zealand there currently appears to be no simplified, effective method of analysing the rotational stiffness of beam-column joints in steel moment resisting frame structures. Many practicing engineers use simplified design tables to detail beam-column joints for strength requirements, without accounting for the flexibility of joints. This tends to underestimate the flexibility of structures and hence the drifts they undergo in wind and earthquake events. To permit improved consideration of beam-column joint stiffness in a simplified manner, this work adapts the European component method to develop a series of tables that practitioners could look up to quickly identify beam-column joint stiffness values. The potential use for such stiffness values is highlighted by examining the impact of joint flexibility on the drifts expected in a 4-storey steel MRF subject to 1 in 500 year return period earthquake loading.

Abstract: In this study, a 12-story reinforced concrete (RC) building with buckling-restrained braces (BRBs) arranged in a zigzag configuration is proposed as a prototype building. The beam-column joint at the tenth floor selected as the sub-assemblage specimen and its details including the BRB gusset bracket and RC corbels were designed following the model building codes. The full-scale sub-assemblage of the structural system was tested using cyclic loading procedure. Test results show that the proposed BRB-to-RC connection details performed very well without failure in the steel gusset bracket or the RC corbels. In order to further study the seismic performance of the 12-story buckling-restrained braced RC frame, nonlinear response history analyses are conducted using a total of 240 (SLE, DBE and MCE) ground accelerations. Analysis results indicate that the maximum ratios of total BRB shear to base shear are about 23% (SLE), 21% (DBE) and 19% (MCE). The maximum inter-story drift ratios under MCE and DBE events are 2.32% and 1.82%, respectively. Analysis results also suggest that the high mode effect is not significant. It is found that the peak demand of the horizontal tension force on the steel gusset bracket can be estimated by considering 70% of the sum of the two horizontal force components computed from the two adjacent BRB maximum tension strengths.

Abstract: Concrete is one of the most resourceful and environmental friendly building materials. It can be cast to fit any structural shape from a cylindrical water storage tank to a rectangular beam, slabs and column in a high-rise building. In RC buildings, portions of columns that are common to beams at their intersections are called beam column joints. Beam-column joints have a crucial role in the structural integrity of the buildings. Review of literature indicates that numerous studies were conducted in the past to study the behaviour of beam-column joints with normal concrete. However, those recommendations are not intended for the fibre reinforced concrete. Some indicates that this material is an alternative to the confining reinforcement in the joint region. So the comparative study of the performance of different fibres in beam column joint has a greater importance and relevance in the field of RCC framed structures. This thesis aims to study the behaviour of beam column joint by evaluating the performance of fibre reinforced concrete. The incorporation of fibres in beam column joint is analysed in this study. The use of different types of fibres such as steel and polypropylene are evaluated.

Abstract: Yingxian Wood Pagoda is the highest standing ancient wood structure in China,with four shorter but stiffer storeys hidden between the five apparent storeys. The beam-colunm joints are highly varied. In this study,a model of typical beam-column joints of the pagoda was simulated in Abaqus. The material used in models was similar to the ones of the pagoda.Non-destructive cyclic loading test of the models under different vertical load were conducted.The hysteretic curves underdifferent vertical load were drawn from the test.And the skeleton curves were obtained by linking all peak moment points of each hysteretic loop. The energy –dissipation performance and bending stiffness of models were derived and discussed.

Abstract: To explore the influence of axial compressive ratio on seismic behavior of reactive powder concrete(RPC) beam-column joints,this paper carry out RPC beam-column joints nonlinear finite element analysis,using software ABAQUS.The effect of different axial compression ratio on the ductility,energy dissipation capacity and bearing capacity are studied,based on hysteretic curves and skeleton curves of the components.The results show that,with the increase of axial compression ratio,skeleton curves of the components tend to be steep when the vertical load of beam ends exceed the peak point.The ultimate bearing capacity of the components are improved with the increasing of axial compression ratio which is less then 0.6,while the ultimate bearing capacity show a opposite trend when the axial compressive ratio exceed 0.6.

Abstract: The seismic performance of RC frame beam-column joints was analyzed by using ANSYS in the paper. Firstly, reasonable finite element models were established by comparing the result of numerical simulation to experiment. Thus the seismic performance of concrete frame joints strengthened by Sprayed FRP was studied, and influence on the seismic performance by different thickness, length of Sprayed FRP, and different axial pressure ratio of column were analyzed in the paper too. Studies showed that reinforcing the concrete frame joints with Sprayed FRP is effective.

Abstract: In order to provide a basis for designing outer annular-stiffener type steel castellated beam (OATSCB) - concrete filled steel tube (CFST) joint, the factors that influence the load-displacement skeleton curve of this kind of joint is analyzed. OATSCB - CFST joint with different influencing factors are designed, and their loading process is simulated by using finite element software ABAQUS. Before simulating, the simulating method is verified by previous test result. The corresponding load-displacement skeleton curves of those joints are also extracted. By comparing these curves in diagram, the following conclusions can be gotten: OATSCB - CFST joint has good seismic performance; steel yield strength, steel ratio and beam to column linear stiffness ratio are the important factors that influences the skeleton curve of this type of joint; opening rate is an important factor for this type of joint to form "strong column weak beam" yield mechanism.

Abstract: The beam-column joint is the key component of a RC structure and also the hub of stress transferring between beam and column. It is the major part for ensuring enough stiffness, ductility and good energy dissipation capacity of the RC frame. In order to simulate the beam-column joints under cyclic loading, a model based on OpeeSees was studied. OpenSees has advantages over other nonlinear analysis software in the improvement of algorithms. Comparison of simulated and observed hysteretic curve indicates that the proposed model is appropriate.

Abstract: Beam-column joints can play a key role on the seismic behavior of reinforced concrete buildings. Until now studies and experimental investigations on this topic have been mainly focused on beam-column joints with stiff beams, i.e. beams with height larger than the thickness of the adjacent floor slab. However, especially in the European residential building stock, frame structures are often equipped with wide - therefore rather flexible - beams. However, not many studies have been devoted so far to this type of connection, therefore an experimental investigation on full scale beam-column joints with wide beam was planned at the University of Basilicata and is currently in progress. In the present paper the main results of two cyclic tests are reported and discussed specifically analyzing the role of the axial load applied to the column on the joint performances and damage mechanisms. Test results highlights that the axial load value has a significant influence of on deformation capacity and ductility behavior.