竹板增强单板层积材组合梁受弯性能

单板层积材加工成梁构件应用于建筑结构材时,由于材料本身的强度和刚度不足,其结构构件不能满足现代多、高层以及大跨度建筑的需求。竹集成材是原竹经过切削成竹片、低温干燥、碳化、涂胶,再同方向平面或侧面组坯、热压胶合而成的竹基复合材料,其力学性能与稳定性优于木材。将集成竹材作为增强材料用于加固单板层积材梁是一种简单有效的提高梁极限承载力的方法。通过进行竹板增强单板层积材组合梁四点弯曲试验,研究了集成竹板对单板层积材受弯性能的增强效果。结果表明,在单板层积材受弯构件上下部粘贴集成竹板可提高构件极限承载力10%～50%。同时,考虑单板层积材和集成竹材料的非线性,推导出了适用于组合梁的极限承载力计算公式,计算结果与试验结果吻合良好。

Bending performance of bamboo-laminated LVL composite beam

Laminated veneer lumber (LVL) is a wood-based composite with stable mechanical properties.Compared with the traditional solid lumber,the LVL is able to sufficiently utilize the wood resource.The laminated bamboo (LB) is a bamboo composite material made by a series of processing technologies.The mechanical properties of bamboo are better than those of wood.The laminated bamboo veneers pasted on upper and bottom sides of the LVL beams may fully utilize the compressive performances of this material and increase the load-carrying capacity of the component.Since the compressive constitutive law of the LVL owns obvious nonlinearity,and the analysis for the ultimate load-bearing capacity of the LB panel reinforced the LVL beams needs to adopt the nonlinear model.The flexural performance of the LVL beams reinforced with the LB panel was investigated in this study.Mechanical performances and failure mode of the LVL bending members with and without the LB reinforcement were studied using four-point bending experiments.The test results showed that the load-carrying capacity of the LVL beams could be obviously improved due to the LB reinforcement.The comparison was conducted by analyzing the ultimate bearing capacity about the LVL bending members with and without the LB panel pasted on the lower surface.By taking into consideration of the nonlinear constitutive relation of the LVL composite,an analytical model was developed to estimate the flexural performances of LB-reinforced LVL beams.The experimental results verified the validity of the developed model.The load-bearing capacities of the LB panel-reinforced LVL beams increased by about 10%-50% when compared with the unreinforced components.The effect of the shear span ratio on the flexural specimen was studied.As the shear span ratio was relatively lower,the shear failure was not observed.The LVL has a long nonlinear segment along the grain compression,and the tension along the straight line always develops linearly,which makes the LVL with obvious nonlinearity.The error of bearing capacity tested and calculated value of flexural members was basically around 10%.The calculated value of the bearing capacity of the single plate laminated timber was in good agreement with the test values,which proved the feasibility of the calculation model of the bearing capacity.