木側撐挫屈束制斜撐（Wood Buckling Restrained Brace, WBRB）以鋼材作為主受力元件、木集成材作為側撐元件。當WBRB使用傳統之十字型斷面作為主受力元件時，主受力元件易發生高模態挫屈導致較大之外撐力，且側撐元件會有相對弱面優先發生開裂。由於在相同之斷面積下，圓管斷面之慣性矩會比十字形斷面大，主受力元件之模態挫屈較低，故本研究使用圓管斷面之主受力元件。為使側撐元件上各個潛在開裂面之開裂潛能相近，故本研究使用圓管斷面之側撐元件。將此形式之WBRB稱為圓管主受力元件WBRB，並於本研究中構思兩種主受力元件消能段建構方式。以ABAQUS對一系列試體進行有限元素分析模擬其受力行為後，可獲得結論如下。

減弱式WBRB之主受力元件整段使用相同圓管，並在消能段均勻開孔以縮減其斷面積，使消能段之軸力強度下降。若選用適當之開孔大小和配置，可使WBRB發揮理想之消能行為並達到預期之軸力強度。但消能段開孔後會導致管壁發生局部挫屈，產生局部面外變形導致側撐元件所受外撐力和摩擦力增加，故本研究中暫放棄此形式。

加強式WBRB之端部段使用比消能段強度更高、厚度更厚之圓管斷面以增加其軸力強度，並以開槽銲連接兩者。在主受力元件長徑比、消能段斷面徑厚比位於指定範圍內時，主受力元件受軸壓力與側撐元件接觸後會發生管壁壓凹之局部變形，主受力元件不會發生高模態挫屈變形，避免側撐元件所受之外撐力增加。雖然主受力元件不會進入高模態挫屈，但側撐元件所受之外撐力仍會導致側撐元件受圓周向拉力而開裂。若要完全避免開裂需大幅增加側撐元件之厚度，故決定以設置束制鋼框改善側撐元件之開裂情形。於側撐元件上均勻設置束制鋼框並施加預力後，此預力會造成側撐元件開裂面間之摩擦力，可以輔助側撐元件在開裂後發揮合成斷面之作用，持續對主受力元件提供相當之挫屈束制能力。本研究中建立束制鋼框配置模式及施加預力之設計方法，並與WBRB既有之設計方法彙整得加強式WBRB之完整設計方法。

Wood Buckling Restrained Brace (WBRB) adopts steel as the main load-carrying element and adopts wood as the lateral bracing element. When WBRB uses a traditional cruciform section as the main load-carrying element, it will experience high buckling mode, leading to higher lateral forces, and the lateral bracing element is more prone to cracking on weaker faces. However, the circular tube section has a larger moment of inertia compared to the cruciform section with the same area of cross section, resulting in lower buckling mode for the main load-carrying element. Therefore, this study adopts circular tube sections as the main load-carrying elements to decrease the potential of high buckling mode. To ensure the potential cracking faces on the lateral bracing element have similar cracking potentials, circular tube sections are also used as the lateral bracing elements. This type of WBRB is called “WBRB With Circular Tube as Core Element”, and two methods of constructing energy dissipating segments in the main load-carrying element are conceptualized in this study. After finite element method analysis using ABAQUS is conducted on some series of WBRB specimens to simulate their behaviors when loaded, the following conclusions are drawn below.

In the weakening-type WBRB, the main load-carrying element adopts a uniform circular tube section throughout its entire length, and energy dissipating segments are created by uniformly perforating the tube to reduce its area of cross section and axial strength. With appropriate perforation size and configuration, the weakening-type WBRB can exhibit desirable energy dissipation behavior and achieve the expected axial strength. However, perforating the tube causes local buckling of the tube wall, resulting in out-of-plane deformations that increase the lateral forces and frictions on the lateral bracing element. As a result, this approach is abandoned in this study.

In the strengthening-type WBRB, the end segments of the main load-carrying element use circular tube sections with higher strength and thicker tube wall than the energy dissipating segments to increase its axial strength, and they are connected by slotted welding. When the length-to-diameter ratio of the main load-carrying element and the diameter-to-thickness ratio of the energy dissipating segments fall within specified ranges, the main load-carrying element undergoes local indentation deformation after contacting the lateral bracing element, avoiding high buckling mode. Nevertheless, the lateral forces on the lateral bracing element still cause circumferential tensile forces which lead to cracking. To avoid cracking, a significant increase in thickness of lateral bracing element is necessary, which will significantly increase the consumption of wood materials, so a restraint steel ring is introduced to improve the behavior of lateral bracing element. By applying uniform restraint steel rings with prestressing on the lateral bracing element, the frictions between the cracking faces assist the lateral bracing element in providing buckling restraint capacity to the main load-carrying element after the lateral bracing element cracks. This study establishes the configuration method and prestressing design method for the restraint steel rings and combines them with existing design methods for WBRB into a complete design method for the strengthening-type WBRB.

[1] 吳合鑫，弧形剪力連接物於圓形CFT及木側撐BRB之試驗行為，國立臺灣科技大學營建工程系研究所碩士論文，2021。

[2] American Institute of Steel Construction（AISC）, “Seismic Provisions for Structural Steel Buildings”, ANSI/AISC 341-16, 2016.

[3] Steven Intardo Oetomo（林烽湧），H型鋼梁塑性鉸段外側封板防挫屈工法，國立台灣科技大學碩士論文，2023。

[4] 中華民國內政部營建署，木構造建築物設計及施工技術規範，2021。

[5] 邵卓平、任海青、江泽慧，木材横纹理断裂及强度准则，2003。