BFRP筋增强胶合木梁受力性能分析

Experimental study on mechanical behaviour of glulam timber beams reinforced with BFRP

为有效提高胶合木梁的抗弯刚度,以东北落叶松为基材,制作了6组(1组未加筋和5组加筋)、每组3根共18根胶合木试验梁,分别对BFRP筋增强胶合木梁和纯胶合木梁的受力性能、破坏形态和极限承载力进行了试验研究,测试了荷载、挠度、应变、裂缝的发生以及发展状况等。同时,根据各试验梁的破坏形态,对比分析了BFRP筋增强胶合木梁和纯胶合木梁的破坏机理及不同配筋率情况下BFRP筋增强胶合木梁的抗弯刚度与极限承载力。结果表明:1)BFRP筋增强胶合木梁和纯胶合木梁的破坏形态类似,均呈现受拉脆性破坏、受拉延性破坏和受压延性破坏三种破坏形态;即配筋率小于0.77%时,BFRP筋增强胶合木梁为受拉脆性破坏,配筋率为0.77%～1.51%时,为受拉延性破坏,配筋率大于1.51%时,为受压延性破坏;且前二者破坏均有明显的裂缝发生、发展过程。2)BFRP筋不仅明显改善了胶合木梁的延性性能,还延缓了胶合木梁的受拉脆性破坏时间,大大提高胶合木梁的抗弯刚度,从而充分发挥梁顶受压区胶合木的强度,同时使胶合木梁的承载能力也得到提高。3)当配筋率增大到超筋后,其承载能力不再继续增大。

In order to effectively improve the flexural rigidity of glulam timber beams,6 groups (1 group unreinforced and 5 groups reinforced,3 beams in each group,a total of 18 beams) of glulam wood test beams were made with Larix gmelinii in northeast of China as the base materials.The mechanical property,failure mode and ultimate bearing capacity of BFRP reinforced glulam timber beams and unreinforced glulam timber beams were studied respectively.The load,deflection,strain,crack occurrence and development were tested. At the same time,the failure mechanism of BFRP reinforced glulam beams and pure glulam beams and the flexural stiffness and ultimate bearing capacity of BFRP reinforced glulam beams with different reinforcement ratios were compared and analyzed according to the failure modes of each test beam.The results show that:1) the failure patterns of BFRP reinforced glulam timber beams were similar to those of glulam timber beams,which showed tensile brittle failure,drawing damage and compressive ductility destruction three kinds of failure forms;When the ratio of reinforcement was less than 0.77%,the BFRP reinforced plywood beam was subjected to tensile brittle failure;When the ratio of reinforcement was 0.77%-1.51%,the BFRP reinforced plywood beam was subjected to tensile ductility failure;When the ratio of reinforcement was greater than 1.51%,the BFRP reinforced plywood beam was subjected to compressive ductility failure;Before the failure,there were obvious cracks and development processes in both beams.2) BFRP tendons not only significantly improve the ductility performance of the glulam beam,but also delay the tensile brittle failure time of the glulam beam,greatly improve the flexural stiffness of the glulam beam,so as to give full play to the strength of the glulam beam in the compression zone at the top of the beam,and at the same time improve the bearing capacity of the glulam beam.3) And when the reinforcement ratio increases to over reinforced,the bearing capacity of the glulam beams will not increase.However,when the ratio of reinforcement increased to superstrength,the bearing capacity of superstrength did not continue to increase.