Investigation on Failure Mechanism of the Standing Seam Metal Roof System

After the introduction of the standing seam metal roof system in China, the research on the force transmission principle and the mechanical performance has not been mature, which is not conducive to the popularization and application of such roofing systems. The problems involved in the upright lock-edge metal roofing system are comprehensive and complex, and require a lot of scientific research to solve them. Based on the above problems, this article targeted the relevant research on the crimping joint of the upright edge-sealing metal roof.
First, the structure of the metal roof is introduced. The wind resistance principle of the roof slab is obtained through the preliminary analysis of the structure of the aluminum magnesium manganese upright metal roofing system:the top roof slab is first deformed upward, and the rising force is transmitted to the occlusion structure. The bearing, the bearing then transmits the load from the self-tapping screw to the purlin, and finally distributes it to the main structure. The order of force transmission is wind-absorbing load→roof panel→fixed support→self-tapping screw→purlin→main structure.
Using non-linear finite element software midas FEA to simulate the whole process of the roof system under the wind load, the wind resistance performance of the vertical locking metal roof system was studied. Combined with the domestic research on the metal roofing system's resistance to wind damage, a uniform load of 2 kN/m² and 5 kN/m² is applied to the roof slab and vertical ribs, and the stress and stress of the roof slab under different loads are analyzed In the deformation situation, the Mises stress cloud maps at different nodes are obtained. Under the uniform load of 2 kN/m², the local connection between the support and the metal hemming due to mutual extrusion and slip, the local stress is large, reaching 220 MPa. But at this time, the middle of the slab still stays at a relatively low stress level; under the uniform load of 5 kN/m², the stress in the middle of the roof slab and the area near the support has reached the yield strength. Under the uniform load of 2 kN/m², the maximum vertical deflection value of the mid-span position of the roof slab is about 48.18 mm, the deflection value is relatively large, and the opening at the support makes the deflection value of the two sides of the panel surface greater than that of the middle panel Its impact on the overall roofing system usage status. When the value of the uniformly distributed wind load applied to the roof panel is 5 kN/m², the mid-span deflection is 220 mm. This is because the roof panel has detached from the support, causing the deflection to rapidly increase. At this time, the excessive deflection to normal use of the panel has an unrecoverable impact. By analyzing the deformation of the roof slab under load, it can be seen that the adjacent roof slabs are moved to the two sides by the curling straight ribs under the wind exposure, and the vertical locking part of the roof slab continuously rubs against the aluminum alloy support extrusion, with the continuous development of deformation, eventually detached from the support. Therefore, under the action of the wind suction force, the bite connection between the curling edge of the roof slab and the support is the first part to be damaged, and special attention should be paid to the need to take corresponding strengthening measures.
Through the modal analysis of the structure, the first five orders of vibration mode and period are obtained. The time history analysis of the wind pressure on the roof slab was performed to obtain the relative displacement response of the lock joint corresponding to each measuring point. In order to improve the wind-resistance ability of the upright locking metal roofing system and prevent partial overturning, corresponding strengthening countermeasures are proposed according to different engineering conditions. After strengthening the treatment, the use safety of the upright lock-edge metal roofing system is improved, which can provide a reference for engineering design.