在中国传统木构建筑中,拼合做法大多见于梁架构件和檩条构件,三架梁、五架梁等梁架构件在承载力或刚度不足时,通常采用梁-角背或梁-随梁枋的拼合做法进行加强,而檩条构件在承载力或刚度不足时,则通常采用檩条-随檩枋的拼合做法加强,拼合做法主要有上小下大和上大下小两种。为研究上小下大拼合木梁的破坏形式、抗弯承载力、截面应变分布,基于传统连接构造做法进行试件设计,对上小下大拼合梁的抗弯性能进行了试验,包括3根杉木梁和3根松木梁。试验结果表明:上小下大拼合木梁受弯破坏模式均为下梁底部木纤维脆性拉断。上下拼合梁的截面应变沿梁截面高度方向的分布均符合平截面假定。最后,基于理论公式推导,结合试验数据修正,提出了上小下大拼合木梁抗弯承载力的计算公式。 In Chinese traditional wooden buildings, most of the splicing methods are found in beam members and purlin members. When beam members such as three girders and five girders are insufficient in bearing capacity or rigidity, beam-angle backs or beams are usually used. The combination method is strengthened, while the strut members in the bearing capacity or rigidity is not enough, it is usually the use of the stripe - with the strokes of the consolidation practice, the main method of splitting the small big and small two. In order to study the failure form, flexural capacity and cross-sectional strain distribution of the upper and lower large-split wooden beams, the design of the specimens based on the traditional connection construction method was carried out. The bending resistance of the upper and lower large-size composite beams was tested, including three Pine beam and 3 pine beams. The test results show that the bending failure modes of the upper and lower large composite beams are the brittle fracture of the wooden fibers at the bottom of the lower beam. The cross-sectional strain of the upper and lower composite beams along the height direction of the beam cross-section are consistent with the assumption of flat section. Finally, based on the deduction of the theoretical formula and the correction of the experimental data, the formula for calculating the flexural capacity of upper and lower large-split wooden beams is put forward.