A delaying and neutralizing procedure of bending brittle fracture of glulam beam with inserted steel plates

布置截面为120mm × 60mm、跨度为216cm（梁高跨度为18）的胶合木梁，截面为40mm × 9mm的钢板插入梁的上缝，并用环氧树脂粘接。另一方面，将一块与上钢板相同截面的钢板插入并粘接在梁的下缝上（a型），两块40mm × 4.5mm截面的钢板插入并粘接在梁的下缝上（b型），最后将三块40mm × 3mm截面的钢板插入并粘接在梁的下缝上（c型）。为此，设计了三种不同受拉侧嵌板布置方式的胶合木梁，并进行了跨中集中荷载试验。然后，这些具有相同的抗弯刚度，因为它们在梁的张力侧具有相同的钢板横截面积。a型梁平均极限荷载为25.9kN， b型梁平均极限荷载为27.1kN， c型梁平均极限荷载为30.7kN。这些极限载荷的不同取决于钢板的屈服点。这是毫无疑问的，因为a、B、C型的荷载-应变曲线在曲线的不同加载点呈现非线性。延性承载力大小依次为c型、b型、a型。综上所述，在抗弯刚度相同的情况下，受拉侧嵌多块钢板的组合梁工程性能更优。

The glulam beams having a cross section of 120mm × 60mm and a span of 216cm (the span by beam height equals 18) are arranged and the steel plates having a section of 40mm × 9mm are inserted to upper slits of beams and are glued with epoxy resin. On the other hand, one steel plate having the same section as upper steel plate is inserted and glued to lower slits of beams (Type-A), two steel plates having a section of 40mm × 4.5mm are inserted and glued to those (Type-B) and finally, three steel plates having a section of 40mm × 3mm are inserted and glued to those (Type-C). As a results, three types of glulam beams having different inserted steel plate layout in tension sides of beams are provided and tested under consentrated load at mid span.Then, these have same bending rigidity, as they have same cross sectional area of steel plates in tension sides of beams. The average ultimate load of three Type-A beams is 25.9kN, that of Type-B is 27.1kN and that of Type-C is 30.7kN, respectively. The different of these ultimate loads are depending to yield points of steel plates. This is no doubt, as the load-srain curves of Type-A, B, C reveal non-linearity at different loading points of the curves. The ductile capacity is also follow the order of Type-C, Type-B and Type-A.As a conclusion, if the glulam beams have same bending rigidity, the type having multiple inserted steel plates in tension side are superior in engineering ability.