轻骨料混凝土-薄壁钢梁组合楼板受火后承载性能试验研究
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摘要
楼板为建筑物的重要构件,其受火后剩余承载性能的研究对于有效指导楼板的火灾后修复和性能评估意义重大。对3块遭受温度为700℃、持续90 min火灾作用后的轻骨料混凝土-薄壁钢梁组合楼板试件开展了静载性能试验。结果表明,尽管火灾作用后组合楼板试件的混凝土已严重开裂、钢梁发生明显屈曲和变形且楼板的整体最大残余竖向位移达到L/80 (L为楼板长度),但组合楼板试件仍具有较高的剩余承载能力,其静载试验的极限荷载达到4.12 k N/m2,中心点的最大挠度达到17.88 mm(L/112),而且未见整体坍塌。对试验结果进一步分析可知:对于双向组合楼板试件,在不改变主梁和预制板相关参数的条件下,采用普通栓钉及钢筋拉结件的组合效果优于采用薄壁异形抗剪键及钢条拉结件;虽然以水泥砂浆为后浇层能够增强组合楼板的整体性、提高整体刚度,但从减轻楼板自重的角度,仍可选用陶粒混凝土作为该组合楼板的后浇层,并可满足组合楼板对承载能力和刚度的基本要求。
Because floors play an important role in buildings,it is of great significance to study the residual bearing capacity of floors after fire for effectively guiding the repair and performance evaluation.Static load tests of the post-fire bearing capacity of three composite floors of lightweight aggregate concrete and thin walled steel beam after exposure to the fire with a maximum temperature of 700 ℃ and a duration of 90 min were completed.The test results show that although the concrete of composite slab specimens has been seriously cracked,the skeleton beams have obviously buckled and deformed after fire,and the maximum residual vertical displacement of the whole slab has reached L/80(L is span of floor),the composite slab specimens still have a high residual bearing capacity:the ultimate load of static load test is 4.12 kN/m2 and the maximum deflection of center point is 17.88 mm(L/112),while no overall collapse is observed.It is further concluded that the two-way composite floor specimens with the ordinary nails for resisting shear and steel bars for joining the concrete panels perform better in terms of bearing capacity and stiffness than that with the Ⅱ-type shearing keys and steel plates.It is seen that although the use of cement mortar as post pouring layer of the composite slabs may have a more obvious effect on improving the post-fire mechanical property of the composite slabs than the use of ceramsite concrete,it is still feasible for the ceramsite concrete to be used as the post pouring layer of the slabs in consideration of decreasing weight of the slabs.It is also shown that the ceramsite concrete may meet the fundamental requirement for bearing capacity and stiffness of the slabs.
Because floors play an important role in buildings,it is of great significance to study the residual bearing capacity of floors after fire for effectively guiding the repair and performance evaluation.Static load tests of the post-fire bearing capacity of three composite floors of lightweight aggregate concrete and thin walled steel beam after exposure to the fire with a maximum temperature of 700 ℃ and a duration of 90 min were completed.The test results show that although the concrete of composite slab specimens has been seriously cracked,the skeleton beams have obviously buckled and deformed after fire,and the maximum residual vertical displacement of the whole slab has reached L/80(L is span of floor),the composite slab specimens still have a high residual bearing capacity:the ultimate load of static load test is 4.12 kN/m2 and the maximum deflection of center point is 17.88 mm(L/112),while no overall collapse is observed.It is further concluded that the two-way composite floor specimens with the ordinary nails for resisting shear and steel bars for joining the concrete panels perform better in terms of bearing capacity and stiffness than that with the Ⅱ-type shearing keys and steel plates.It is seen that although the use of cement mortar as post pouring layer of the composite slabs may have a more obvious effect on improving the post-fire mechanical property of the composite slabs than the use of ceramsite concrete,it is still feasible for the ceramsite concrete to be used as the post pouring layer of the slabs in consideration of decreasing weight of the slabs.It is also shown that the ceramsite concrete may meet the fundamental requirement for bearing capacity and stiffness of the slabs.
引文
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[2]陈安英,完海鹰,孙磊,等.钢筋桁架组合楼板抗弯性能试验研究[J].建筑结构,2015,45(8):59-63.(CHEN Anying, WAN Haiying, SUN Lei, et al.Experimental study on bending behavior of steel bar truss composite slab[J]. Building Structure,2015,45(8):59-63.(in Chinese))
[3]陈一欧,刘季康.压型钢板组合楼板耐火性能试验研究[J].建筑结构学报,1998,19(5):22-27.(CHEN Yiou, LIU Jikang. Experimental study on fireresistance performance of profiled steel sheetingconcrete composite slabs[J]. Journal of Building Structures,1998,19(5):22-27.(in Chinese))
[4] GUO S,BAILEY C G. Experimental behaviour of composite slabs during the heating and cooling firestages[J]. Engineering Structures,2011,33(2):563-571.
[5]王新堂,周明,王万祯.压型钢板-陶粒混凝土组合楼板火灾响应及火灾后受力性能试验研究[J].建筑结构学报,2012,33(2):10-17.(WANG Xintang,ZHOU Ming,WANG Wanzhen. Experimental study of fire response and post-fire mechanical performance of profiled sheet-ceramsite concrete composite floor[J].Journal of Building Structures,2012,33(2):10-17.(in Chinese))
[6]王新堂,周明,王万祯.轻骨料混凝土组合楼板的火灾响应及火灾后性能研究[J].自然灾害学报,2012,21(2):200-206.(WANG Xintang,ZHOU Ming,WANG Wanzhen. Study on fire response and post-fire behavior of lightweight aggregate concrete composite floor[J]. Journal of Natural Disaster,2012,21(2):200-206.(in Chinese))
[7] ELLOBODY E. Composite slim floor stainless steel beam construction exposed to different fires[J].Engineering Structures,2012,36:1-13.
[8] FIKE R,KODUR V. Enhancing the fire resistance of composite floor assembles through the use of steel fiber reinforced concrete[J]. Engineering Structures,2011,33(10):2870-2878.
[9] TAN K H,NGUYEN T T. Experimental and numerical evaluation of composite floor systems under fire conditions[J]. Journal of Constructional Steel Research,2015,105:86-96.
[10] MCALLISTER T P. Sensitivity of composite floor system response at elevated temperatures to structural features[J]. Engineering Structures,2014,58:115-128.
[11] NGUYEN T T,TAN K H. Ultimate load of composite floors in fire with flexible supporting edge beams[J].Journal of Constructional Steel Research,2015,109:47-60.
[12]王新堂,杨景,王万祯.开孔薄壁钢梁-轻骨料混凝土装配式组合楼板受力性能试验研究[J].建筑结构学报,2016,37(5):39-47.(WANG Xintang,YANG Jing, WANG Wanzhen. Experimental study of mechanical property of the composite slabs of ceramsite concrete and thin-walled steel beams with openings[J].Journal of Building Structures,2016,37(5):39-47.(in Chinese))
[13]丁发兴,应小勇,余志武.轻骨料混凝土单轴力学性能统一计算方法[J].中南大学学报(自然科学版),2010,4(5):1973-1979.(DING Faxing, YING Xiaoyong,YU Zhiwu. Unifiled calculation method of uniaxial mechanical properties of lightweight aggregate concrete[J]. Journal of Central South University(Science and Technology),2010,4(5):1973-1979.(in Chinese))