预应力混凝土空心叠合板耐火性能试验和理论研究

EXPERIMENTAL AND THEORETICAL STUDY ON FIRE RESISTANCE OF PRE-STRESSED CONCRETE HOLLOW COMPOSITE SLAB

  • 摘要: 预应力混凝土空心叠合板(简称“叠合板”)是由预制预应力混凝土空心板做底板,上面整体浇筑钢筋混凝土面层叠合而成,在装配式建筑中得到广泛应用。为探明现浇层纵向钢筋配筋率及布置方式对预应力混凝土空心叠合板耐火性能的影响,考虑单跨受火工况,对3个足尺两跨预应力混凝土连续叠合板进行耐火试验,得到受火跨横截面温度分布、内力重分布、裂缝及挠度发展规律,基于试验结果获得了试件的耐火极限和现浇层纵向钢筋配筋率及布置方式对试件耐火性能的影响大小。为了弥补试验中存在的不足和获得更大范围参数的影响规律,使用ABAQUS建立叠合板耐火分析模型,根据试验数据进行了验证,进而分析了不同配筋率及不同钢筋布置方式的叠合板在ISO-834标准升温条件下的火灾响应。结果表明:叠合板可以达到2小时耐火极限;预制预应力空心板隔热性能良好;相同受火和荷载条件下,提高现浇层纵筋配筋率能显著提升叠合板耐火性能;保持钢筋用量相同时,增大负弯矩区配筋率并合理设置负弯矩钢筋长度,能有效提高叠合板耐火性能;负弯矩区配筋率对火灾下叠合板内力重分布影响较大;升温速率大的试件挠度随温度的增长缓慢。

     

    Abstract: Pre-stressed concrete hollow composite slab (hereinafter referred to as "composite slab") is made of prefabricated pre-stressed concrete hollow slab as the base plate with the reinforced concrete surface layer being poured integrally above it, which is widely used in prefabricated buildings. In order to find out the influence of the longitudinal reinforcement ratio and layout of the cast-in-place layer on the fire resistance of pre-stressed concrete hollow composite slabs with the consideration of the fire exposure of single span, fire resistance tests were carried out on three full-size two span pre-stressed concrete continuous composite slabs, based on which the development laws of temperature distribution in the cross section, internal force redistribution, cracks and deflections of the fire exposed span were obtained. Based on the test results, the influence of the fire endurance of the specimens and the ratio and arrangement of the longitudinal reinforcement in the cast-in-place layer on the fire resistance of the specimens is obtained. In order to avoid the shortcomings in the test and obtain the influence law of a wider range of parameters, ABAQUS was used to establish the fire resistance analysis model of the composite slab, which was verified according to the test data, and then the fire response of the composite slab with different reinforcement ratios and different reinforcement arrangements under the ISO-834 standard fire was analyzed. The results show that the composite slab can reach the fire endurance limit of 2 hours. Prefabricated pre-stressed hollow slab has good thermal insulation performance. Under the same fire and load conditions, increasing the ratio of longitudinal reinforcement in the cast-in-place layer can significantly improve the fire resistance of composite slabs. When the amount of reinforcement is the same, increasing the reinforcement ratio in the negative moment area and reasonably setting the length of the negative moment reinforcement can effectively improve the fire resistance of the composite slab. The reinforcement ratio in the negative moment area has a great influence on the redistribution of internal forces of composite slabs under fire. The deflection of the specimen with large heating rate is slow with the increase of temperature.

     

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