Fire Performance of Timber-Concrete Composite (TCC) Systems in Mass Timber Buildings

在一个充满了制造工程木材制成的大型木型材的可能性的新时代，即胶合板(Gulam)、交叉层合板(CLT)和钉合板(NLT)型材，这些型材的强度和结构完整性在火灾中可以保持更长的时间。因此，世界各地越来越多地建造了几座主要由木材建造的高层建筑。这类建筑的楼板系统甚至可以变得更坚固，跨越更长的距离，使设计师在楼层规划方面拥有更大的通用性，并通过增加由混凝土制成的顶层，允许在使用足够的剪力连接的情况下形成木材-混凝土组合(TCC)楼板体系，从而促进现代建筑的开放式概念设计。在这种复合系统中，有效地利用了这两种材料的有利机械性能，因此，与仅由CLT或NLT面板制成的木地板相比，可以实现更坚固的地板系统的几个优点。在使用TCC地板系统的几个优势中，包括更高的强度、耐用性，以及大大改善的声学和振动性能特性。不幸的是，在火灾条件下的TCC系统的实验工作不像在环境温度下那样广泛，因此需要进一步研究的一个非常重要的领域是TCC地板系统在火灾条件下的行为，重点是某些方面。例如，以前对TCC地板系统的大多数实验研究都是小尺寸、小数量和/或代表单向地板组件；而在拟议的研究计划中，将在火灾条件下检查二十四(24)个使用CLT和NLT面板的大型TCC双向板式地板组件。此外，很少有研究涉及板间连接对TCC楼板体系结构耐火性能的影响，因此，带有CLT板的试验组件将包括板间花键连接。此外，在TCC楼板周围使用由胶合板梁组成的支撑框架系统来增强混凝土楼板在火灾中的膜作用，这在现有的文献中从未出现过。因此，相信拟议的研究计划将导致：开发新的可靠的实验数据，并可能在CSA O86标准的未来版本中实施火灾条件下的TCC板式地板体系设计模型(科学影响)；开发能够模拟那些具有所选剪切连接的TCC地板组件在火灾条件下的实际行为的有限元模型(技术影响)；通过开发新的设计模型间接支持加拿大木材工业(经济影响)；以及允许加拿大人建立更坚固、可持续的材料制造和防火安全的大批量木材建筑(社会影响)。

In a new era full of possibilities for manufacturing large timber sections made of engineered wood, i.e., glued-laminated timber (glulam), cross-laminated timber (CLT) and nailed-laminated timber (NLT) sections, strength and structural integrity of such sections can be retained for much longer time in fire. As a result, several tall buildings made primarily of timber are increasingly being constructed worldwide. Floor systems in such buildings can even be made stronger and span longer distances to allow designers greater versatility in terms of floor plan and promote for open concept design in modern buildings by adding a top layer made of concrete that allows the formation of Timber-Concrete Composite (TCC) floor systems with the use of sufficient shear connections. In this composite system, the advantageous mechanical properties of both materials are efficiently utilized and thus, several advantages can be achieved for a more robust floor system, if compared to timber floors such as those made solely of CLT or NLT panels. Among the several advantages of utilizing TCC floor systems are greater strength, durability, and much improved acoustics and vibration performance characteristics. Unfortunately, experimental work on TCC systems in fire conditions is not as extensive as at ambient temperature, and thus one very important area that warrants further investigation is the behaviour of TCC floor systems in fire conditions with focus on certain aspects. For instance, most previous experimental studies on TCC floor systems were of small size, small number and/or representing one-way floor assemblies; whereas in the proposed research program, twenty-four (24) large-scale two-way TCC slab-type floor assemblies utilizing CLT and NLT panels will be examined in fire conditions. Also, it is very rare to find research studies that address the effect of inter-panels joint connections on the structural fire behaviour of TCC floor systems, and thus those test assemblies with CLT panels will include spline panel-to-panel connections. In addition, the use of a supporting framing system made of glulam beams along the perimeter of the TCC floor slab to enhance the membrane action of the concrete slabs in fire is something that has never been presented in the available literature so far. Therefore, it is believed that the proposed research program will lead to: development of new and reliable experimental data and possible implementation of design models for TCC slab-type floor systems in fire conditions in the future version of CSA O86 standard (scientific impact); development of FE models that can simulate the actual behaviour of those TCC floor assemblies with the selected shear connections in fire conditions (technological impact); indirectly support the Canadian wood industry through the development of new design models (economic impact); and allow more robust, sustainable material-made, and fire safe mass timber buildings for Canadians (social impact).