- 學位論文
實尺寸兩層樓夾型挫屈束制斜撐鋼構架在變軸力下之中等韌性構件箱型鋼柱耐震實驗
Seismic Tests of Full-Scale, Two-Story Steel Sandwiched Buckling-Restrained Braced Frames with Moderately Ductile Built-Up Box Columns under Varying Axial Load
摘要
本研究延續陳冠維 (2019)、熊厚淳 (2020)及沈厚寬 (2022)的研究，將進一步研究空心箱形鋼柱 (Hollow Box Column，HBC)在構架中的耐震行為。實驗試體為兩組兩層樓夾型挫屈束制斜撐構架 (Sandwiched Buckling-Restrained Braced Frame, SBRBF)，各組試體分別由兩根寬厚比接近的HBC柱組成，並在實驗當中分別加以高軸力及低軸力以觀察鋼柱在不同軸力下的耐震行為。所有試體柱，梁及斜撐核心構件皆由SN490B鋼材製作。試體一南柱與北柱之寬厚比分別為20.5及21.1，皆小於美國AISC 341 (2016)規定的高韌性λhd及中等韌性λmd之平均斷面寬厚比限制，以下簡稱為λad (b/t = 21.7)。試體二南柱與北柱之寬厚比分別為27.4及27.5，皆小於美國AISC 341 (2016)規定的中等韌性λmd斷面寬厚比限制。通過實驗可以發現試體一以美國AISC 341 (2016) λad平均斷面寬厚比作為設計依據，其鋼柱在一樓層間側位移角0.04 rad下行為仍然良好，構架之側力抵抗能力也均未下降。試體二之實驗結果顯示若以美國AISC 341 (2016)規定的中等韌性λmd斷面寬厚比為限制來進行挫屈束制斜撐構架鋼柱的設計，構架之中高軸力之南柱在一樓層間側位移角0.02 rad第一迴圈柱底彎矩就已下降超過最大值之90 %，並且柱底開始嚴重挫屈，代表不能以此寬厚比限制來進行BRBF中鋼柱之設計。實驗當中也將會分別對柱挫屈，軸向變形及斜撐接合板等局部效應進行分析及探討。
並列摘要
This study continued the work of Chen (2019), Xiong (2020), and Shen (2022), and will further study the seismic behavior of build-up Hollow Box Columns (HBCs) in the frame. The experimental specimens are two groups of two-story Sandwiched Buckling-Restrained Braced Frames (SBRBF). Both columns in the same frame will have similar width-to-thickness (b/t) ratio and will apply different axial load ratio on the top of the column to observe the seismic behavior of steel columns under different axial load. All columns, beams and BRB cores are made of SN490B steel. The width-to-thickness (b/t) ratio of the specimen 1 columns are 20.5 and 21.1 respectively, which are both smaller than the average width-to-thickness ratio limits for high ductility λhd and moderate ductility λmd section specified by AISC 341 (2016), hereinafter referred as λad (b/t = 21.7). The width-to-thickness ratio of two steel columns in specimen 2 are 27.4 and 27.5 respectively, which are both smaller than the moderately ductile λmd width-to-thickness ratio limit specified by AISC 341 (2016). Through the experiment, it can be found that columns in specimen 1 which are designed based on the average width-to-thickness ratio of AISC 341 (2016) which is λad, has good behavior even in 0.04 rad story drift angle. For specimen 2 columns which have width-to-thickness ratio of 27.4 and 27.5 respectively, the experimental results show that the column with high initial axial load can not fulfill the minimum requirement of 0.02 rad story drift angle with bending moment dropped not more than 90% of the maximum value. The column bottom will also buckle seriously with significant vertical displacement. This means that the design of columns in BRBF cannot be carried out with this width-thickness ratio limitation. In the experiment, the local effects of column buckling, axial deformation, frame behavior, and diagonal brace gusset will be analyzed and discussed respectively.