以鋼纖維混凝土簡化 BRB 與RC 構架接合之模擬與分析

Abstract

挫曲束制支撐(BRB)已經廣泛運用在鋼結構建築之中，但在鋼筋混凝土建築中之利用仍然較少，在有限的接合案例中，預埋鐵件方法因其穩定之接合效果而得到了最多的學術注目。唯BRB往往連接在鋼筋混凝土(RC)構架之梁柱不連續區，恰為箍筋最密集區域，因此若要預埋額外鐵件進入RC構架中將會使施工過程更加複雜。過往研究指出，若在混凝土中加入鋼纖維，能顯著提高混凝土材料韌性和剪力強度。這能減少RC梁柱端對於橫向箍筋量的需求，降低鋼筋籠綁紮的繁瑣，使BRB在連接上更為簡單和方便，未來無論是補強亦或是新建構架都能有更大的發展。 因此本研究進行一簡化配置實驗探討鋼纖維混凝土與BRB連接之效益[謝昀庭，2025]。主要有三大設計重點，一為梁柱接頭和梁端改用鋼纖維混凝土；二為BRB與RC構架接合僅在梁端；三為控制梁端塑鉸位置。本研究利用SAP2000、ABAQUS等有限元分析軟體針對實驗細節和改動進行模擬，提供詳細之模型設定細節和操作流程，並將模擬結果與實際實驗結果進行比較，以提出鋼纖維接合BRB構件之設計方法和模擬流程。 分析結果顯示使用鋼纖維混凝土接合BRB能在較少箍筋用量和接合步驟條件下，維持與一般BRB接合RC構架相同破壞模式，BRB先產生塑鉸，再來才是RC構架的破壞。實際試驗中之力量分布與模型模擬結果大致相同，唯試驗中因試驗施作相關問題使柱在2%降伏，柱降伏後之彎矩傳遞導致接合段梁亦有降伏情況產生，並非先前預測之接合段外部梁降伏內部保持彈性。此外，最終BRB在5% 拉力破壞，力量大幅下降，此時RC構架之破壞行為為梁柱接頭剪力破壞，本研究認為是因BRB僅接在梁端，對梁端和梁柱接頭造成可觀之水平力和垂直力，使得梁柱接頭預測失準，成為最終發展破壞之弱面。 本研究最後提出相關模擬修正建議和未來實驗之可能修正方法，使模擬結果得以更加貼近實際結構行為。

Buckling-Restrained Braces (BRBs) have been widely adopted in steel structures due to their excellent energy dissipation capacity. However, their application in reinforced concrete (RC) structures remains limited. Among the few existing connection strategies, embedded steel plates have attracted academic attention due to their stable performance. However, BRBs are typically installed at D-region of RC beam-column joints, which are areas of dense transverse reinforcement. Embedding additional steel components into such congested regions complicates construction procedure. Previous studies have shown that combining steel fibers into concrete significantly enhances its toughness ratio and shear strength. This improvement reduces the need for dense transverse reinforcement in beam-column joints, alleviating reinforcement congestion and simplifying BRB connection details. As a result, this approach holds great promise for both retrofitting and new construction. This study conducts a simplified configuration experiment to explore the effectiveness of connecting BRBs using steel fiber reinforced concrete (SFRC) [Hsieh, 2025]. The experiment focuses on three major design modifications: First, using SFRC at beam-column joints and beam ends; Second connecting the BRB only to the beam ends, instead of the beam-column joint; Third, Controlling the plastic hinge formation at the beam ends. Finite element simulations were performed using SAP2000 and ABAQUS to replicate the experimental setup and modifications. The study provides detailed modeling procedures and compares simulation outcomes with physical test results to propose a practical design and modeling framework for BRB-SFRC connections. Analysis results show that using SFRC enables BRB-RC connections to maintain stable during cycling load. That the plastic hinging of the BRB occurred first and followed by RC frame, even with reduced stirrup ratios and simplified connection details. However, due to testing execution issues, yielding accidently occurred in the column at 2% drift, which led to moment transfer and unexpected yielding at the connection zone of the beam. This deviated from the anticipated behavior where yielding place of beam should occur outside the connection region while the connection zone remained elastic. Eventually, BRB’s tensile failure occurred under 5%, with a sudden drop in horizontal force. At this stage, the RC structure experienced shear failure at the beam-column joint. It’s because the BRB being connected solely at the beam end, inducing considerable horizontal and vertical forces that were underestimated in the design, making the joint the weakest point of failure. The study concludes by proposing revised modeling recommendations and experimental improvements to better align future simulations with actual structural behavior.