通讯机构：
[Jiejun Wang] S;School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
timber-steel composite beam;bending performance;bolt area ratio;interface slip;flexural bearing capacity
摘要：
The present paper investigates the impact of bolt distance, bolt diameter, and the number of bolt rows on the bending performance of timber-steel composite (TSC) beams. This study aims to facilitate the application of bolt connections in assembled TSC structures. Composite steel I-beams were designed with timber boards connected in the upper section with bolts. Three-point static bending tests were conducted on nine timber-steel composite beams divided into four groups (L1, L2, L3, and L4) with varying bolt arrangements. The destruction mode, ultimate bearing capacity, ductility coefficient, load-midspan deflection curve, and load-midspan strain curve of each specimen were obtained. In addition, the destruction mechanism, the quantitative relationship between the bolt area ratio and interfacial slip, and the ideal bolt area ratio were identified. It was found that when the midspan deflection of the timber-steel composite beam approached the prescribed limit, the main failure mode can be explained as follows: The top surface of the boards of all the specimens had longitudinal local splitting, except L1, which had fewer bolts and no obvious damage. Moreover, due to compression and because the stress at the lower edge of the I-beam entered the flow amplitude stage, some of the specimens were crushed but were not pulled off. The composite beams had high flexural load capacity and ductility coefficient, and the maximum relative slips of the timber-steel interfaces were in the range of 2-6 mm. It was also found that the maximum slip of the interface and the ductility coefficient decreased steadily as the bolt area ratio increased, while the specimen's flexural bearing capacity increased. The optimal bolt area ratio was determined to be 8 x 10(-3). Using the total bolt area, we designed the arrangement of the bolts on the board. For convenience, multiple bolt variables were converted into one bolt variable. The longitudinal distance of the bolts had a greater impact on the slip, and the bolt diameter had a smaller impact. The theoretical values of total relative slip were found to be in good agreement with the experimental results, which were based on the superposition of the relative slip equations with varying bolt distances. The effective bolt area ratio and the formula of the relative slip of each segment can provide instructions for the arrangement of bolts and the control of the relative slip of intersections in engineering practices.
作者机构：
[Wang, Jiejun; Peng, Quan; Liu, Ruiyue] Cent South Univ Forestry & Technol, Sch Civil Engn, Changsha 410004, Peoples R China.;[Wu, Zhenzhen] Xiangtan Univ, Sch Civil Engn, Xiangtan 411100, Peoples R China.;[Peng, Quan] China Railway City Construct Grp Construct Technol, Xiangtan 411100, Peoples R China.;[Zhang, Yu] Taizhou Xintong Informat Technol Co Ltd, Taizhou 225312, Peoples R China.
通讯机构：
[Ruiyue Liu] S;School of Civil Engineering, Central South University of Forestry and Technology, Changsha 410004, China<&wdkj&>Author to whom correspondence should be addressed.
关键词：
BFRP reinforcement;glued wood hollow columns;axial pressure test;destruction mode and mechanism;effective area ratio
摘要：
The present paper investigates the impact of basalt fiber reinforced polymer (BFRP) on the axial compression performance of glued wood hollow cylinders. This study aims to facilitate the application of BFRP in the field of structural reinforcement of glued wood hollow columns. Ten glued laminated wood hollow columns of the same size were designed and placed into five groups (ZC1 and ZRC2 to ZRC5), of which one group (ZC1), with a total of two pure wooden columns, was not arranged with BFRP, and the remaining two wooden columns in each group were arranged with BFRP at different distances. The destruction mode, ultimate load capacity, load-displacement curve, load-strain curve, and ultimate load capacity-total area of the BFRP paste curve of each specimen were obtained by conducting axial compression tests on five groups of wood columns reinforced with different basalt fiber cloths, which revealed the damage mechanism, the relationship between the ultimate load capacity and total area of BFRP paste, and pointed out the most effective area ratio. The test results show that the destruction mode of axially pressed, glued, laminated wood hollow columns is typical compression buckling damage, mainly manifested as follows: the wood at the middle or end of the specimen under pressure first buckles; then, with the increase in load, the specimen is crushed; at this time, the maximum ultimate bearing capacity of each specimen is in the range of 296.77 similar to 375.85 kN, the maximum longitudinal displacement is in the range of 2.77 similar to 3.38 mm, and longitudinal cracks appear at the end. It is worth noting that the growth rate of the ultimate bearing capacity varies with the increase in the total area of the BFRP paste. When the total area of the BFRP paste is less than a 3.2 x 10(5) mm(2) range value, the growth rate of the ultimate bearing capacity is faster, and then, the growth rate gradually becomes slower. The optimum BFRP paste area ratio can be taken as k = 0.59. The ultimate bearing capacity after reinforcement increases from 11.06% to 26.65% compared with the pure wood column. According to GB50005-2017, "wood structure design standards" improve the hollow wood column bearing capacity calculation method and fit the BFRP reinforced hollow wood column's ultimate bearing capacity calculation formula; the errors are within +/- 10%, which can provide a reference for the practical application of BFRP in the field of reinforcing glued wood hollow cylindrical structures.
通讯机构：
Hunan Engineering Laboratory for Manufacturing and Application Technology of Modern Timber Structural Engineering Materials, Central South University of Forestry and Technology, Changsha, Hunan, China
