Study on Collapse Optimization of Weak Axis Moment Connections

Abstract

3D Weak axis moment connections are the connections between the beam with the web of an I section. But these connections are weaker as they are connected to the web which are thinner portions of the I section compared to flanges. This can lead to buckling of flanges. A new reduced beam section (RBS) connection, consisting of radius cuts in the beam flanges and circular openings in the beam webs, is proposed to allow for more ductile connections. RBS connections may increase structural deflection and crack width in the steel frame structure under large deformations. Therefore, it is extremely important to consider the bearing capacity and progressive collapse resistance of steel frame structures with RBS connections. Progressive collapse analysis of weak axis moment connections without any improvisation is taken for analysis and their collapse location and collapse resistance studied. To enhance weak joint connection design and to delay collapse time, we introduce reduced beam sections. Curved cell reduced beam sections are modeled and analysis is performed for various thickness of cell and by changing diameter. Thus, an effective size was obtained by combining the results with the conventional and the effective location of weak axis is improved.

Introduction

I. INTRODUCTION

Steel frame structures with ordinary weld connections often suffer from brittle fractures; design of steel connections has a great effect on the seismic performance of the whole steel structural system. Moment Resisting Frames (MRF) are efficient framing systems under seismic loads. MRF systems provide high ductility and high energy dissipation. However, they perform very low elastic stiffness and cause high labour work. RBS beam approach, another strategy introduces openings in beam webs to form a plastic hinge away from the connections to make beams more ductile. In a beam column joint, when the beams are connected to the flange of an I section then they are called strong axis moment connections. They are so called because when the beams are connected on to the web, they are more thinner sections than flange and the load transferred from the beam is getting directed to a much thinner section which results in buckling.

Conclusion

From the above analysis done using ANSYS Workbench following conclusions were made: 1) In A50 B130 C10 connections, while varying the thickness the A50 B130 C10 T4 connection is taking more load and is considered as effective section. 2) In A50 B130 C25 connections, while varying the thickness the A50 B130 C25 T4 connection is taking more load and is considered as effective section. 3) From the above cases thickness 4mm provides an effective section, as it takes more load compared to the other cases. 4) When thickness 4mm is made constant and when the other parameters were varied the section NC CP A 75 B130 C25 T4 gave an increase load of 119.56% when compared to normal RBS section. Therefore, the section take up more load when compared with other sections. 5) Other sections also gave increased load carrying capacity when compared with normal RBS section that shows that curved plate RBS seems to be effective compared with Normal RBS.

References

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Copyright

Copyright © 2023 Maria Pius, Mr. Krishnachandran V N. 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.