TNCBF1-R-HSS: Taiwan Non-Seismic Concentrically Braced Frame (NCBF) with Repaired First Story and HSS Braces

The specimen designated TNCBF1-R-HSS consisted of a single-bay two-story concentrically braced frame with inverted V-bracing (chevron configuration) and a weak first story beam relative to the design post-buckled brace unbalanced load in the 2010 AISC Seismic Provisions. This frame was intended to be representative of a repaired non-seismic concentrically braced frame (NCBF) using in-plane buckling HSS braces. In-plane buckling braces could significantly reduce the gusset plate interface weld demands by eliminating out-of-plane gusset plate deformation. From the damaged TNCBF1-N-HSS speicmen, the first story braces and gusset plates were replaced with new HSS braces and connections compliant with SCBF design. Net section reinforcement plates were added to the second story corner brace connections but no other repair was made to the second story. Despite the in-plane buckling design, the first story braces buckled out-of-plane. The specimen was loaded quasistatically through the second story slab under a reversed cyclic increasing amplitude loading protocol. Traditional instrumentation and newer optical sensors were installed on the specimen. Portions of the specimen were whitewashed to detect yielding.

编号为TNCBF1-R-HSS的试验试件为单跨两层中心支撑框架，采用倒V形支撑（人字形布置），其首层梁相较于2010年美国钢结构协会（American Institute of Steel Construction, AISC）抗震规程中设计的屈曲后支撑不平衡荷载对应的要求存在刚度薄弱问题。该框架旨在代表采用面内屈曲空心截面支撑（Hollow Structural Section, HSS）修复后的非抗震中心支撑框架（non-seismic concentrically braced frame, NCBF）试件。面内屈曲支撑可通过消除节点板的面外变形，显著降低节点板界面焊缝的受力需求。从受损的TNCBF1-N-HSS试件中，首层支撑与节点板被更换为符合特殊中心支撑框架（Special Concentrically Braced Frame, SCBF）设计要求的新型空心截面支撑及连接节点。研究人员在二层角落支撑连接节点处增设了净截面补强板，但未对二层其余部位进行修复作业。尽管采用了面内屈曲设计，首层支撑仍发生了面外屈曲。该试件通过二层楼板施加拟静力荷载，采用变幅往复循环加载制度。试件上布设了传统测试仪器与新型光学传感器。对试件部分区域进行了白垩涂装，以观测屈服变形。