特殊韌性桁架抗彎構架(Special Truss Moment Frame, STMF) 為一種具有良好消能行為之構架。空腹構架(Open-web Truss Moment Frame)雖然具有節省成本、接頭設計簡單等等優點，但在過去之地 震經驗中發現此種結構之抗震行為不佳。自從1989 年開始，密西根 大學的研究人員對此種構架進行一連串的分析試驗並進行改良，提 出的特殊桁架抗彎構架具有兩種型式，其一為交叉拉桿式 (X-Diagonal Configuration)，另一種為威廉地爾式(Vierendeel Configuration)。 然而不論是威廉地爾式或交叉拉桿式，皆於特殊 段上下弦桿產生塑性鉸，進而產生大量變形。由於其與非特殊段之 接合方式為固接，因此於破壞後之維修、更換不易。為此，本研究 於特殊段斜桿採用僅受拉之鋼棒，避免桿件挫屈造成構架於小位移 時強度損失，同時搭配摩擦消能機制，提供更佳之消能容量並可於 相同強度要求下減小鋼棒尺寸，構架亦可於鋼棒斷裂後維持穩定之 承載效能。研究結果顯示，此設計確可達到減少破壞區域並於震後 容易更換之效果，亦能保留充足之構架強度及消能行為，因此應為 一有效之耐震設計方案。;Special Truss Moment Frame is an effective structural form that adopting open-web truss design. The advantages of open-web truss moment frame include the lower cost and easier beam-column joint design. However, the seismic behavior of such system is questionable, because of the buckling concern of web member in early stage of the load application. This system has been investigated by researchers from the University of Michigan. Two types of modification, the x-diagonal configuration and the Vierendeel frame, have been proposed. Although the x-diagonal configuration and the Vierendeel frame have been proven to possess high strength, the plastic hinges occur at the upper and bottom chords of special segment remain a concern. This study focused on the further improvement of special truss moment frame by using the steel bar and friction mechanism in the special diagonals. It was found from the test results that the proposed steel bars were subject to tension only during the cyclic loading, therefore the buckling could be avoided. Further observation on the responses validated that the friction mechanism effectively dissipated energy and maintained the structural stability after the steel bars were fractured. The above phenomena demonstrated the effectiveness of the proposed design method.
