Innovative nail laminated timber-concrete composite floor deck system

在过去的10年里，人们对由混凝土板和木梁组成的复合木地板系统的开发进行了大量的研究，这些木板和木梁通过剪切连接件连接在一起。这种类型的复合材料系统的另一个稍有不同的版本是使用在梁和混凝土板之间插入的交叉叠层木材(CLT)或结构复合材料木材(SCL)面板。这一修正概念源于在大跨度楼盖施工中广泛应用的压型钢-混凝土板组合体系。木板作为混凝土板的模板，减少了混凝土板的厚度。由于CLT和SCL的成本相对较高，这种两层甲板系统的经济性令人望而却步。 在这项研究中，将开发一种更具成本效益的双层桥面系统，由异型钉层压板(NLT)和钢筋混凝土板组成。异形NLT面板是通过用更深的木材钉住2x3(38 Mm X 63 Mm)木材制造的。在结构上，异型材可以提供一个剪力键，以增强与混凝土板的组合作用，特别是在横向上。 从生产的角度来看，这个甲板系统可以使用简单的工具，如钉枪和夹子，以及未充分利用的2x3木材资源来生产。第一阶段的研究将开发最优的产品格式和结构细节。木材和混凝土的基本成分将由相对较低等级的材料组成。两名博士生将在头3年从事该产品开发阶段的工作。在第三年年底，预计将解决以下参数：1.适合NLT的钉子模式；2.最佳的NLT型材几何形状，包括交替的2x3和更深的木材；3.使用轻型紧固件在混凝土和型材NLT之间使用合适的机械剪切连接件；4.连接相邻面板的适当细节；5.最大楼层跨度潜力。 第二阶段将在第4年和第5年进行，将调查两个问题。第一个是两层桥面系统与支撑木梁或钢梁之间的连接细节。重点将放在重型紧固件的使用上，如钢销。第二个要研究的问题是两层桥面系统本身的振动性能以及由两层桥面和支承梁组成的整个楼盖系统的振动性能。研究结构的振动性能是非常重要的，因为众所周知，对于大跨度楼盖系统来说，振动舒适性很可能是结构设计的主导因素。这一阶段将由2名硕士学生进行。如果这个项目的结果显示甲板系统具有潜在的商业可行性，将进行一个更全面的项目，该项目将开发更精细的制造程序，并检查其他性能问题，如消防和声学。

A substantial amount of research has been conducted over the past 10 years on the development of composite timber floor systems consisting of a concrete slab and timber beams that are connected using shear connectors. A slightly different version of this type of composite systems is to use a cross laminated timber (CLT) or structural composite lumber (SCL) deck inserted between the beams and concrete slab. This modified concept originated from the profiled steel-concrete slab composite system which is widely used in long-span floor construction. The wood deck serves as formwork for the concrete slab and reduces the thickness of the concrete slab. The economics of such a 2-layer deck system is prohibitive due to the relatively high cost of CLT and SCL. In this research a more cost-effective 2-layer deck system consisting of a profiled nail laminated timber (NLT) panel and a reinforced concrete slab will be developed. The profiled NLT panel is fabricated by nailing 2 by 3 (38mm x 63mm) lumber with deeper lumber. Structurally, the profiled NLT can provide a shear key to enhance composite action with the concrete slab, especially in the transverse direction. From the production perspective, this deck system can be produced using simple tools, such as nail guns and clamps, and an under-utilized resource of 2x3 lumber. The first phase of the research will develop the most optimum product format and construction details. The basic components of lumber and concrete will consist of relatively low-grade materials. Two PhD students will work on this product development phase in the first 3 years. At the end of year 3, it is expected that the following parameters will be resolved: 1. Suitable nailing patterns for the NLT; 2. Optimum NLT profile geometry consisting of alternating 2x3 and deeper lumber; 3. Suitable mechanical shear connectors between concrete and profile NLT using light fasteners; 4. Suitable details for connecting adjacent decking panels; 5. Maximum floor span potential. In the second phase, which will be conducted in years 4 and 5, two issues will be investigated. The first one will be the connection details between the 2-layer deck system and the supporting timber or steel beams. Focus will be on the use of heavy duty fasteners, such as steel dowels. The second issue to be investigated will be the vibrational performance of the 2-layer deck system on its own and that of the complete floor system consisting the 2-layer deck and supporting beams. It is important to study vibrational performance because it is well known that for long-span floor systems, vibration serviceability likely governs the structural design. This phase will be conducted by 2 MSc students. If the results from this project show potential commercial viability for the deck system, a more comprehensive project, which will develop more refined fabrication procedure and examine other performance issues such as fire and acoustics, will be pursued.