鋼梁接SRC柱之梁柱接頭力學行為之數值模擬分析

Abstract

近年來許多大尺寸之「鋼梁接SRC柱」之梁柱接頭(Steel Beam-to-Steel Reinforced Concrete Column Connections，簡稱「S-SRC接頭」)的反復載重耐震試驗結果顯示，此種梁柱接頭擁有良好的耐震能力。然而，由於進行大尺寸試驗必須消耗相當的時間、人力與成本，因此以數值模擬分析之方式日漸成為瞭解梁柱接頭力學行為的另一種選擇。本研究採用ANSYS有限元素分析軟體，針對五組實尺寸S-SRC梁柱接頭之反復載重試驗結果進行數值模擬分析。首先，依據試驗之實尺寸試體建立其數值分析模型，其次將數值分析結果與試驗結果進行比較與討論。 分析結果顯示，由於鋼梁插入SRC柱內的部份受到接頭區混凝土的有效束制，使得鋼梁可以於SRC柱混凝土面外發展出良好的塑性鉸，且其發生位置遠離梁柱接頭內部之銲道，可有效避免銲道發生脆性破壞。研究結果顯示，經過適當設計之S-SRC梁柱接頭其鋼梁端部不須經由補強或減弱(切削鋼梁翼板斷面)之方式，即能發揮預期之強度與韌性；同時亦因鋼梁不須切削或補強，有助於節省梁柱接頭區之鋼梁製作成本。另一方面，ANSYS之分析亦證實在梁柱接頭區之H型鋼柱腹板加銲適當之疊合板，可有效提昇梁柱接頭區之剪力強度與抵抗剪力變形的能力，進一步減少梁柱接頭區混凝土開裂的情形。本研究亦初步證實，於SRC梁柱接頭區加銲足夠厚度之疊合板以取代接頭區之圍束箍筋大致上是可行的，此種作法將有助於簡化接頭區箍筋施工之複雜性。整體而言，本研究經由ANSYS分析S-SRC梁柱接頭力學行為之結果與前人之試驗結果大致相近，顯示本研究建立之數值分析模型可得到合理的模擬結果，並證明此種S-SRC梁柱接頭在適當的設計下具備良好的耐震能力。

During the past decade, many test results of steel beam-to-steel reinforced concrete column (S-SRC) connections have shown satisfactory seismic performance. However, due to the fact that the cost of conducting full-scale experiment is expensive and time consuming, an alternative approach using the numerical simulation technique has become increasingly desirable. The objective of this research is to use the highly recognized finite element method (FEM) computer software ANSYS to numerically simulate the mechanical behavior of the S-SRC connections. In the first stage, a FEM model simulated the SRC test specimen were generated and analyzed. The numerical results were compared to the SRC test data to confirm the validity of the FEM model. In the second stage, the parameters related to the design of the S-SRC connections were investigated using the valid FEM model obtained from the previous stage. The numerical results showed that the reinforced concrete in the connection zone provided “effective constraint” to the steel beam which was embedded in the SRC column. This constraint helped the steel beam to develop plastic hinge right out the SRC column face, and the welded joint can be protected from premature failure. In addition, the ANSYS analysis also confirmed that welding doubler plate on the web of the H-shaped steel can effectively promote the shear strength and reduce the concrete cracking in the connection zone. The aforementioned analysis suggested that it is feasible to substitute the doubler plate for the hoop reinforcements in the SRC connection zone. Finally, it is hoped that the results of this numerical investigation could provide further understanding on the mechanical behavior and the seismic performance of the S-SRC connections.