BRB及SCB鋼構架含滑動樓板雙向振動台試驗: 構架設計及實驗

Abstract

本研究探討滑動消能樓版系統於雙向地震作用下之可行性與耐震效益，並比較不同水平裝置對構架整體行為之影響。試驗採用實尺寸一層樓鋼構架進行振動台試驗，構架南北向配置自復位斜撐（Self-Centering Brace, SCB），東西向則採用夾型挫屈束制斜撐（Diagonal Buckling-Restrained Brace, DBRB）搭配抗彎構架（SMRF）所構成之二元抗側力系統（Dual System）。本試驗共分為四階段，前兩階段於構架與樓板之間分別安裝水平夾型挫屈束制支撐（HBRB）及摩擦型消能裝置（FD），第三階段以高勁度 T 型鋼桿模擬傳統固接樓板，作為滑動樓板系統之對照組；第四階段則拆除所有斜撐，以觀察構架系統極限行為。 為實現滑動樓板於雙向地震下之面外運動能力，本研究將水平裝置之端部改為鉸接設計，使其於面外方向可自由轉動。試驗採用2022年台東池上地震（EYUL）東西向地震歷時，並依據PGA進行比例縮放，最大振動台輸入達0.73g。結果顯示，滑動樓板系統於雙向輸入下能有效發揮，且第一與第二階段試驗皆於 0.8×DBE 等級開始出現相對滑移，證實滑動行為之可行性與穩定性。與固接樓板相比，滑動樓板在 DBE 及 MCE 級距下皆有效降低構架側位移與基底剪力，尤以摩擦裝置階段（Phase 2）之減震效果最為顯著。 此外，試驗結果與 ASCE 7-22 標準中 Method 2 採用不同 Rs值之設計剪力預測趨勢相符，顯示其對滑動與固接樓板系統皆具良好預測性，較傳統 Method 1 設計較為精確及保守。加速度反應方面，第三階段試體樓板與構架運動趨於一致，顯示地震能量直接傳遞至樓板；反觀滑動樓板系統則能有效減緩樓板震動反應，並降低傳遞至構架之慣性力。自復位斜撐（SCB）於震後可有效抑制殘餘變形，顯示其具良好回復性能，而斜撐之面外穩定性方面，SCB表現較DBRB穩定，DBRB於端部出現些許面外變形趨勢，為設計上需留意之重點。

This study investigates seismic performance of a sliding energy dissipation floor system under bidirectional earthquake loading and compares the influence of various horizontal connection devices on the overall behavior of the structural frame. Full-scale shake table tests were conducted on a one-story steel frame. The lateral force-resisting system consists of a self-centering brace (SCB) in the north-south direction and a dual system in the east-west direction, composed of diagonal buckling-restrained braces (DBRBs) and a special moment-resisting frame (SMRF). The experiment was divided into four phases: in the first two phases, the floor was connected to the frame using horizontal buckling-restrained braces (HBRBs) and friction devices (FDs), respectively. The third phase replaced the horizontal devices with high-stiffness T-shaped steel bars to simulate a traditional fixed floor system, serving as a control. In the fourth phase, all bracing members were removed to observe the frame’s limit-state behavior. To enable out-of-plane movement of the sliding floor under bidirectional excitation, the end connections of the horizontal devices were designed as pinned joints, allowing free rotation during out-of-plane motion. The tests utilized the east-west ground motion record from the 2022 Chishang earthquake (EYUL) in Taitung, Taiwan, scaled to multiple PGA levels, with the peak table input reaching 0.73g. The results demonstrated that the sliding floor system effectively engaged under bidirectional input, with relative sliding observed in Phases 1 and 2 starting at 0.8×DBE. Compared to the fixed-floor configuration, the sliding system significantly reduced lateral displacement and base shear forces at both DBE and MCE levels, with the friction device (Phase 2) showing the most pronounced damping effect. Furthermore, the experimental results aligned well with the predicted design base shear using Method 2 of ASCE 7-22, which incorporates reduction factors (Rs) for different floor systems. Method 2 provided accurate and conservative predictions for both sliding and fixed floors, whereas Method 1 underestimated the demand in all cases. In terms of acceleration response, the floor and frame moved synchronously in Phase 3, indicating direct energy transmission to the floor, while the sliding systems in Phases 1 and 2 effectively reduced the floor’s acceleration and inertial force transfer. Post-earthquake residual drift was minimal in the SCB-equipped direction, indicating excellent recentering performance. Regarding out-of-plane stability, the SCB showed more favorable behavior than the DBRB, which exhibited minor out-of-plane deformation at brace ends—a consideration that must be addressed in design.