胶合木连续梁抗弯性能试验研究

Experimental research on flexural behavior of continuous glulam beams

为探讨胶合木连续梁的抗弯性能。以国产速生东北落叶松为基材,加工并制作了4组12根两跨胶合木连续梁,分别开展跨中集中荷载试验,并与相同设计参数的胶合木简支梁进行对比试验。通过实测各组梁的极限承载力与极限位移、荷载-跨中竖向位移曲线,定量分析胶合木连续梁在跨中荷载作用下的抗弯性能;并以梁的截面高度、梁的结构类型为参变量,研究其对胶合木梁抗弯刚度的影响。验证胶合木梁基本符合平截面假定后对比计算了胶合木连续梁、简支梁的弯矩-曲率曲线和跨中挠度。试验与计算结果表明:胶合木连续梁破坏形态为,中支点上缘发生受拉破坏,下缘发生局部受压破坏。相同条件下胶合木连续梁的极限承载力较简支梁提升了10.47%~22.48%,极限位移降低7.41%~24.37%,胶合木连续梁的抗弯刚度明显大于简支梁。胶合木连续梁和简支梁的弯矩−曲率曲线理论值与试验值基本吻合,连续梁弯矩−曲率曲线斜率明显大于简支梁。胶合木梁的跨中挠度计算值与试验值吻合较好。胶合木梁从简支梁过渡到连续梁,抗弯极限承载力与抗弯刚度大幅提升。理论分析结果表明,胶合木连续梁较简支梁在相同变形条件下所承受的截面弯矩更大,抗弯性能更好。

The flexural behavior of the continuous glulam beams was explored.The domestic fast-growing Northeast Larch was taken as the material.Four groups of 12 two-span continuous glulam beams were processed and manufactured,and central-span load testswere carried out.Comparative tests were conducted with simply supported glulam beams by the same design parameters.The measurements were made for the ultimate bearing capacity,ultimate displacement,load-mid-span vertical displacement curve,quantitative analysis of the flexural behavior of the continuous glulam beams under mid-span load.The height of the beam section,and the type of beam structure were used as parameters to research their influence on the flexural rigidity of glulam beams.After verifying that the glulam beams conform to a flat section’s assumption,the bending moment-curvature curves,and the mid-span deflection of the continuous glulam beams and the simply-supported beams were compared and calculated.The results are drawn.1)The failure mode of the continuous glulam beams is a tensile failure at the upper edge of the middle fulcrum and local compression failure at the lower edge.2)Under the same conditions,the maximum bearing capacity of the continuous glulam beams are 10.47%~22.48%higher than the simply supported beams,and the ultimate displacements are reduced by 7.41%~24.37%.The bending rigidity of the continuous glulam beams are significantly greater than that of the simply-supported beams.3)The theoretical values of bending moment-curvature curves of continuous glulam beams and simply-supported beams agree with the experimental values.The slope of the bending moment-curvature curves of continuous beams are noticeably greater than the simply-supported beams.4)The calculated values of the deflection of the glulam beams in the middle of the span are in good agreement with the experimental values.The glulam beams transition from simply supported beams to continuous beams,their ultimate flexural bearing capacity,and flexural rigidity are significantly improved.Theoretical analysis shows that the glulam continuous beams can bear more section bending moments than simply-supported beams under the same deformation conditions,and their bending performance are better.