冷弯薄壁型钢增强复合材料夹层梁受力机理与设计方法研究

The traditional composite sandwich structures used in civil engineering fields mainly use lightweight and lower modulus materials as core material, which results in the ultimate strength of the structure was controlled by the stiffness of the cross-section rather than controlled by strength of the materials, and the strength of the FRP material was limited to full play. This program proposed a novel sandwich structure—composite sandwich beams reinforced with thin-willed cold-formed steel, in which the thin-willed cold-formed steel was embedded in the light-weight core, to increase the beam stiffness and ultimate strength. The thin-willed cold-formed steel and the FRP face sheets were connected by shear connectors. This project aiming at the specific problem of using in major civil infrastructure, from two levels about interface structure and structural system, researchs the innovation combination theory, develop the key interface connection method between FRP and cold-formed thin-willed steel. Study the transfering force, connection and the pattern of interface damage of structural composites, reveals its mechnical behavior under bending and shear loads. And based on experiment results, establishs the beam stiffness and bearing capacity theory analysis model, proposes the deflection and load bearing capacity calculation formula of the new structure, gains its design method of normal use and load bearing capacity limit state. The implement of this program builds theoretical basis for application and dissemination of this new composite structural system in structure beam and slab elements.

传统土木工程领域用纤维增强复合材料夹层结构主要以模量较低的轻质材料作为芯材，使其允许承受的设计荷载实际由截面刚度控制，而非强度控制，限制了纤维材料强度的充分发挥。本项目提出一种新型复合材料夹层结构——冷弯薄壁型钢增强复合材料夹层梁，即在轻质芯材内部嵌入冷弯薄壁型钢，以提高其剪切刚度和承载力，薄壁型钢和纤维面板之间采用剪力键连接。项目针对制约该新型结构在土木工程领域应用的关键科学问题，从界面构造和结构体系两个层次深入研究其创新组合理论，得到该新型梁界面、连接、传力的损伤演化规律，揭示其在弯、剪荷载作用下的受力机理；基于构件试验研究结果，深入开展理论分析，建立其刚度和承载力理论计算模型，提出该新型结构挠度和极限承载力计算公式，得到其正常使用和承载力极限状态设计方法。本项目的实施，为该新型结构复合材料体系在建筑梁、板构件中的推广应用提供科学依据和设计参考。

传统土木工程领域用纤维增强复合材料夹层结构主要以模量较低的轻质材料作为芯材，使其允许承受的设计荷载实际由截面刚度控制，而非强度控制，限制了纤维材料强度的充分发挥。针对上述问题，本项目具体开展以下工作：（1）提出了一种新型复合材料夹层结构——冷弯薄壁型钢增强复合材料夹层梁，即在轻质芯材内部嵌入冷弯薄壁型钢，以提高其剪切刚度和承载力，薄壁型钢和纤维面板之间采用剪力键连接，并对其制备工艺进行了创新研究；（2）开展了冷弯薄壁型钢增强复合材料夹层梁弯曲、压缩、剪切性能试验研究，得到了其典型破坏模式；（3）建立力学分析模型，得到了刚度和变形计算公式，分析了截面应力的分布规律，针对典型破坏模式提出了相应的承载力计算方法，并开展了关键技术集成与示范工程应用。