Strengthening of RC Beam-Column Joints Using Steel Plates and Shear Connectors

Abstract

The role of a beam?column joint is very vital in RCC framed structures. Most of the structural collapses due to earthquakes have been initiated by the failure of the beam?column joints and therefore understanding the behavior of beam?column joints is important. The beam column joint is a crucial area where loads from the beam and columns are transferred. It becomes the most critical part of the structure when poor detailing ,unsafe design adopted in the region ,overuse or lack of maintenence. Large numbers of retro?tting techniques are being adopted worldwide to strengthen the beam?column joint. Analytical modelling of interior and exterior beam-column joint has been modelled by using finite element analysis software ANSYS to validate the performance. In the proposed technique beam column joint were modeled using steel plate and steel plate with shear connectors. For structural safety, especially for reinforced concrete beam–column joints, strength of the joints has to be increased. The test results show that the performance of the joints was improved by using the proposed method.

Introduction

I. INTRODUCTION

Most of the damages to existing reinforced concrete infrastructure are due to inadequate design, overuse and/or poor maintenance. Hence strengthening/retro?tting of such structures has become one of the most demanding construction activities. As far as RCC framed structures are concerned, the beam?column joints are crucial elements which are prone to failure. Arun Raj Ebanesar [3] They shows that experimental and analytical investigation improvement in seismic   performance was found in the beam column joint by providing wire mesh and steel plate, which absorbs the lateral input energy more than the conventional joint. This method can be effectively used as new earthquake resistant construction. Sasmal and Voggu [20] Studied the quality of RC beam-column joints is considered by two variety of internal beam-column joints. The shear strength of the joints is tested analytically using the method of soft strut and tie.It is reflected by the analysis that subsequent energy dissipation per cycle drift offers a lot better perspective than the cumulative energy dissipation. The proposed technique Strengthening of Beam-Column joint using steel plates and shear connectors is introduced. Internal strengthening of beam column joint processing with parametric study. From the parametric study an optimum dimension for steel plates is obtained. The results proving that the joint performance improved by increased load carrying capacity of the joint and the failure location that also moved from the joint.

II. OBJECTIVE

To perform nonlinear FEA of beam column joint with internal strengthening using steel plate under various parametric study subjected to monotonic loading.

1. Effect of plate length
2. Effect of plate Height
3. Effect of plate Thickness
4. No of plates (Single,Double)

III. METHODOLOGY

The main goal of this project is to strengthen the Beam-Column joint using steel plate and shear connectors under various parameters and to investigate the performance of the joint by internal and exteernal strengthening. The study's primary goal is to use the ANSYS WORKBENCH software to analyse and compare the performance and determine the ultimate load, deflection and the failure location.

A. Modelling of Structure

The Beam-Column joint specimen was modeled using ANSYS Workbench. The proposed conventional model is shown in fig 1. A monotonic displacement was applied to the beam to analyse the performance of joint and to identify the failure location. The grade of concrete in the frame members was M25 with the specified characteristic compressive strength of 25 MPa and the grade of reinforcement is Thermo-mechanically Treated(TMT) bars with the specified yield strength of 415 MPa. Modulus of Elasticity of concrete Ec = 15000MPa, Characteristic strength of concrete fck = 25MPa, Poisson’s        Ratio = 0.2, Modulus of Elasticity of steel Es = 210000MPa. All columns of the study are chosen to be size 200mmx300mm and height 2300mm. whereas, the size of the beam sections is considered as 200mmx300mm and height 900mm. The design for shear reinforcement in beam and column sections was carried out as per IS 456:2000 design provisions. The FEM model of specimens is shown in Fig 1 to 2.

Conclusion

A Beam column joint with steel plate is designed. Beam column joint with various length, height, thickness and different number of plates are modelled and they are allowed to testing under monotonic loading. 1) Steel plates having varying length 50mm, 100mm, 150mm and 200mm are studied. From this study it is observed that almost 9.29% of load is increased. Beyond 150mm the load carrying capacity is not very much improved. Hence 150mm is the effective length of steel plate can be used inside for the strengthening of beam-column joint. 2) Steel plates having varying height 100mm, 150mm and 200mm are studied. From this study it is observed that almost 12.4% of load is increased. Beyond 150mm the load carrying capacity is not very much improved. Hence 150mm is the optimum height of steel plate can be used inside for the strengthening of beam-column joint. 3) Steel plates having varying thickness 5mm, 10mm and 15mm are studied. From this study it is observed that almost 11.5% of load is increased. There is no much changes observed in load carrying capacity while doing the parametric study using changing the thickness. So minimum 5mm thickness is recommended for the improvisation of joint strengthening. 4) Placing the plate with different number, it is observed that upto 12% of load is increased. The optimum performance is observed on the plate with two numbers. Beyond two numbers, placing three plates has no significant improvement in performance. Hence the steel plate having 400(150)x150x5 with two number of plates are considered the optimum dimensions for internal strengthening of beam-column joint. 5) From the analysis the optimum dimension of steel plate is 400(150)x150x5. Two number of steel plates having length 400mm, height 15omm and thickness 5mm is recommended for the Beam-Column joint strengthening.

References

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Copyright

Copyright © 2023 Sreelakshmi Babu, Amna . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.