切削式鋼梁與高強度鋼筋混凝土圓柱接頭耐震行為

Abstract

本研究旨在探討兩種不同梁柱交會區鋼骨型式之RCS梁柱接頭，於搭配短托梁與續接鋼梁切削設計下，能否展現良好之耐震行為。 本研究共進行三座鋼梁與高強度鋼筋混凝土圓柱內部接頭試體反復載重試驗，試體參數為梁柱交會區鋼骨型式與鋼梁翼板寬厚比，交會區鋼骨型式分別為圓鋼管連續型與橫隔板連續型，交會區為橫隔板連續型者再以鋼梁寬厚比為參數，以探討該型式接頭於不同鋼梁斷面之適用性。 因本研究所採用之RCS梁柱接頭型式，鋼梁須於柱面與短托梁末端兩彎矩需求較大斷面進行接合，因此三座梁柱接頭試體皆以減弱式接頭進行設計，採用國內常用之梁翼梯形切削型式，並根據過去相關研究，將切削區域之預期材料強度與材料應變硬化等因素納入考量，使鋼梁於柱面與續接處發展之彎矩不超過預期塑性彎矩強度。 實驗結果顯示，交會區鋼骨型式為圓鋼管連續者，其中一側梁柱接頭因鋼梁續接位置之螺栓未能鎖緊至預張力值而提前失敗，交會區鋼骨型式為橫隔板連續者，於採用之設計方法與細節下，則皆能通過AISC 341-16(2016)對於耐震系統梁柱接頭之變形與強度要求，另根據實驗結果，推論鋼梁翼板寬厚比對於此型式梁柱接頭所造成之影響於位移角4%之前並不顯著。

This study aims to investigate the seismic performance of two different kinds of RCS beam-column joints with short beam stub and reduced beam section connections design. The focus is on examining whether these connections can exhibit good seismic behavior. This study conducted cyclic loading tests on three specimens of steel beam to high-strength reinforced concrete circular column interior joints. The specimen parameters included the joint details of the steel part and the width-to-thickness ratio of the steel beam flanges. Two types of joint details were considered: through-tube and through-diaphragm-plate. For the through-diaphragm-plate type, additional parameters included the width-to-thickness ratio of the steel beam. The goal was to investigate the applicability of this type of joints to different steel beam sections. Due to the adopted types of RCS beam-column joints in this study, it is necessary to connect the steel beam at locations experiencing higher bending moments, specifically at the column face and the end of the short beam stub. Consequently, all three beam-column joint specimens were designed with a weakening type of connections. This design incorporates the commonly used trapezoidal cut in the beam flanges in Taiwan, while also taking into account the expected material strength and strain hardening in the region where the beam flanges are trimmed. The goal is to ensure that the probable maximum moments developed at the column face and where steel beam is connected do not exceed the plastic moment based on the expected material strength. According to the experimental results, for the through-tube type specimen, premature failure occurred as the bolts at the steel beam splicing location did not tighten to the pre-tension value. On the other hand, for the through-diaphragm-plate type specimens, under the adopted design methods and details, all specimens met the deformation and strength requirements for beam-to-column connection of seismic force-resisting system outlined in AISC 341-16 (2016). Additionally, the experimental results also indicate that the impact of the flange width-to-thickness ratio on the behavior for this type of beam-to-column connection is not significant before reaching a drift angle of 4%.