钢-混凝土组合梁抗火性能试验研究

对两种组合梁形式:主梁式试件(压型钢板肋平行于钢梁)和次梁式试件(压型钢板肋垂直于钢梁)分别进行了抗火试验。试验中量测了试验炉火升温过程,试件的温度和跨中挠度。通过对试验结果的分析发现:由于混凝土板有明显的阻热作用,组合梁中的混凝土板升温较慢,钢梁升温较快,导致钢梁截面温度分布不均匀;由于高温和外力共同作用下,在梁端发生混凝土抗剪破坏,而栓钉由于受到混凝土的保护,温度较低,栓钉仍能正常发挥抗剪连接作用;跨中挠度达到梁跨的1/30后,变形快速增大,随之在跨中形成一条横向贯穿混凝土楼板的主压溃裂缝,产生塑性铰并形成机构,使简支组合梁产生不适于继续承载的变形,达到破坏。

Experimental study on the fire-resistance of steel-concrete composite beams

Fire-resistant tests of two types of steel-concrete composite beams are presented.One is"main beam type"test,in which the steel beam is parallel to the rib of metal deck,and the other is"secondary beam type"test inwhich the steel beam is perpendicular to the rib of metal deck.During the test,the furnace temperature,temperature of different sections of the specimens and mid-span deflection are measured.The conclusions are as follows: 1) the temperature of the concrete slab rises much slower than that of the steel beam,and has a great influence on temperature distribution of cross section of the steel beam due to the low thermal conductivity of the concrete slab;2) due to the high temperature and imposed load,shear failure of the concrete occurs possibly at the end of the beam.However,shear studs remain intact thanks to the protection from the concrete slab;3) once the mid-span deflection reaches 1/30 of the beam span,the deflection will rapidly and continuously increase until a distinguished crush crack occurs in the concrete slab,named as"plastic hinge"formed in the mid span of the specimens.