Investigations On Shear Performance Of Splice Plates Connected Castellated Beams

Castellated beam refers to H-shaped steel beams with web openings.Traditional castellated steel beams are mostly made by cutting and rewelding of steel H-shaped beams.The processed castellated beams not only have higher strength and stiffness than the original H-shaped steel beams,the structural self-weight has also been reduced.At the same time,pipes and equipment can pass through the web openings,thereby the building height can be reduced.At the same time,due to the discontinuity of the web,three new failure modes,including web-post bulking,Vierendeel mechanism,weld damage,have been generated.This paper proposes two new types of splice plates connected castellated beams(SPCB),which are Bolted Castellated Beams(BCSB)with octagonal web openings,a welded SPCB with rectangular web openings.Compared with traditional castellated beams,the castellated beams connected by splicing plate are convenient to transport,and the upper and lower T-shaped parts can be transported separately;the beam height can be adjusted by changing the height of the splicing plates;ribbed splicing plates can be used to improve the shear buckling capacity of the web-posts.The residual stress caused by welding and secondary cutting during manufactory can be avoided in BCSB with octagonal web openings.The SPCB with rectangular web openings can be produced by simply welding T-beams and the splicing plate without cutting H-beams,which is much more convenient during production.In this paper,the finite element method is used to study the shear behavior of the two kind of splice plates connected castellated beam.The mechanical properties of BCSB with octagonal web openings are compared with welded castellated beams of the same size.Studies have shown that the h BCSB with octagonal web openings have no weaker mechanical properties than welded castellated beams.The research parameters included the width-to-thickness ratio of the web-posts,the number of bolts,the layout of the bolts,and the stiffeners.There are three failure modes of BCSB with octagonal web openings:bolt damage,combination of bolt damage and web-post bulking,web-post bulking.The welded stiffeners on both sides of the splicing plate can significantly improve the web-post buckling performance of the castellated beams.Two methods,namely Strut Model and the wedge-shaped sub-model method,were used to calculate the shear buckling capacity of the castellated beam,and the calculation accuracy of the two theoretical approach was compared in this paper.The shear capacity of castellated beams failed in Vierendeel mechanism was also calculated by equivalent rectangular method.At the same time,the formula of failure limit between the failure modes of BCSBs with octagonal web-openings is also given.In the study of the shear performance of SPCBs with rectangular openings,the research parameters included hole shape,the splice plate connection form,the splicing plate overlap length,the web thickness,and the hole height.The splice plate connection forms include splice plate with and without and without stiffening ribs The stiffening ribs can obviously improve the shear bearing capacity of the castellated beam.The behavior of SPCBs is significantly different from the failure characteristics of ordinary castellated beams with circular and hexagonal web openings.The strength is determined by the ultimate shear capacity of T-beams above and below the rectangular openings.In this paper,the formulas for calculating SPCBs with rectangular openings with and without stiffening ribs are given respectively.