Experimental Research On Bending Properties Of Laminated Bamboo Beam Under Fire

As a traditional building material,bamboo has many advantages,such as environmental protection,renewable,fast growing and high yield.The laminated bamboo made from it has excellent processability and mechanical properties.It is a promising high strength biomass structural material.However,the flammability of bamboo seriously restricts the development of laminated bamboo in the field of architectural structure.In order to promote the engineering application of laminated bamboo,the mechanical properties,flame retardancy treatment,carbonization speed and fire resistance limit of laminated bamboo are studied in this paper.The main contents and results include the following aspects:(1)The bamboo fiber was treated by pressure impregnation method with flame retardants,and the effect of flame retardant treatment on laminated bamboo was studied through mechanical properties test and carbonization test.Finally,it was concluded that the flame retardant treatment could reduce the carbonization speed of the laminated bamboo.However,due to the adverse effects of flame retardant treatment on the strength of materials,the fire resistance of the specimens is not improved.(2)Through a single and three face fire test,the carbonization speed of R-laminated bamboo board and T-laminated bamboo board in burning 20 min,40min and 60 min was studied,and the falling situation of the laminated bamboo was observed.The carbonization speed formula of the two directions of the laminated bamboo was analyzed and summed up,which provided the basis for the theoretical analysis and finite element simulation of the subsequent fire resistance limit.(3)Through the three point bending test,the bending performance of laminated bamboo beams at normal temperature is studied and the theoretical design method of bending strength of laminated bamboo beams is obtained by finite element simulation analysis.It is concluded that the bending design of the laminated bamboo beam is controlled by deformation rather than strength,and its span limit deflection is l/ 250.The ratio of carrying capacity under the span deflection of l/ 250 and strength of the laminated bamboo beam is very small,generally not more than 30%(4)The fire resistant limit of the laminated bamboo beam is studied by the bending test of the laminated bamboo beam under the fire,and the fire resistance design method suitable for the laminated bamboo beam is deduced in combination with the design method of the European standard on the beam.