Beam-column Junctions Research Articles

Equivalent Ductility Damage Model for Seismic Response of RC Structures: Test and Verification

. It is possible to quantify the damage to reinforced concrete members under cyclic loading through a nondimensional parameter known as a “damage index”. The damage index can be either a global damage index for the total structure, or a local damage index for the element level. In this paper, a new damage model termed “equivalent ductility damage model” has been suggested for evaluation of the damage index, which is consistent with accepted definitions of ductility. Substructure method was applied to verify the suggested new damage model. A total of 3 identical half-scale reinforced concrete columns were tested under variable amplitude cyclic loading up to the ultimate failure of the specimens. The imposed displacement histories were obtained from analytical simulations of the model column subjected to a series of earthquakes. Test observations indicate that the proposed model predicts 100 percent damage at the ultimate failure state of the element. The proposed damage index model can be extended to other structural elements, such as shear walls, beams, beam-column junctions, etc.

ANALYSIS OF CORNER BEAM-COLUMN JUNCTION WITH INCLUSION OF THE EFFECT OF CONSTRUCTION JOINTS

This paper describes a comparison between beam-column junctions with and without construction joint, also, a parametric study deals with construction joint is presented by taking various conditions of the junction. These include the various positions of the construction joint, the axial load on the column, strength of concrete in the second cast and the amount of dowels crossing the joint. By developing a computer program which was originally written by Dr. Ihsan Al-Shaarbaf (1990), (P3DNFEA, program of three dimensional nonlinear finite element analysis), to consider the effect of construction joint depending on the fact that the shear force can be transmitted across the shear plane either by interlocking of the aggregate particles protruding from each face or by dowel action of the reinforcement crossing the cracks by using Fronteddu’s and Millard’s models, respectively. It is concluded that the construction joints existed in the beam-column junctions result in a significant reduction in the in-plane shear stiffness and it would affect only on the rotation and shear strains of the joint.

Simplified procedure for seismic analysis of asymmetric buildings

A simplified procedure, which is a modification of the shear beam model, has been developed and applied to treat the seismic analysis of asymmetric buildings. This three dimensional procedure accounts for torsional coupling and the bending rotations at beam–column junctions and it can be used with a personal computer to give fast and reasonably accurate results, which compare well with those from comprehensive finite element analysis. This procedure will therefore be useful for preliminary seismic analysis and design of buildings.

Numerical Study Of Structural Joints ReinforcedWith Composite Fabrics

The structural application of composite materials such as fiber reinforced plastics (FRP) has increased in recent years. The FRP products can be used in the initial construction or for repair and structural enhancement. FRP materials have several advantages over steel including, light weight, corrosion resistance, and the ability to mold FRP overlays to concrete surfaces. FRP overlays have been used to strengthen/repair both concrete beam and column elements. Limited studies have been performed on the use of FRP overlays at beam-column connections. Joints that are reinforced with FRP overlays have a different failure mode than FRP plated beams or wrapped columns. At the beam-column connection the interface is subjected to prying or peeling stresses. This investigation involves parametric studies of the application of FRP overlays to exterior beam-column connections for enhancement of structural performance. Different composite materials and different overlay configurations are used. The choice of the composite materials affects the structural performance. Materials that are considered are E-glass, kevlar, and graphite. Configurations studied include overlays bonded to the tensile faces with and without wraps. Numerical analysis shows that the bond stress perpendicular to the overlay/concrete interface at the beam-column junction can easily exceed the tensile strength of the underlying concrete. Therefore, the configuration of the FRP overlay plays an important role in the prevention of peeling. Transactions on Engineering Sciences vol 21, © 1998 WIT Press, www.witpress.com, ISSN 1743-3533

Damage Model for Reinforced Concrete Elements under Cyclic Loading

It is possible to quantify the to reinforced concrete members under cyclic loading through a nondimensional parameter known as a damage The index can be either a global index for the total structure, or a local index for the element level. In this paper, the limitations of existing local models are discussed. A new is proposed, which is consistent with accepted definitions of ductility and which takes into account at least two equal amplitude cycles at each displacement level. A total of 23 reinforced concrete beam elements were tested under monotonic and cyclic loading up to the ultimate failure of the specimens. Based on the test results, a simple relation termed modified Park's model has been suggested for evaluation of the index. The proposed predicts 100% at the ultimate failure state of the element. The proposed index can be extended to other structural elements, such as shear walls, columns, and beam-column junctions.