Investigation On Pre-stressed Concrete Arch Bar Roof By Loaded Test

The pre-stressed concrete arch board roofing is a new type of roofing structure which is practiced widely in granary construction for its reasonable stress, large span, and the capability of insulation and moisture proofing. This essay will present a case of one-storey granary adapted with such type of roofing with its planar size of 24m x 78m, and roofed by 40 frames of pre-stressed concrete arch boards. The pre-tensioned concrete board spans for 24m, arc rise is 2.4m in height, and 2m in width. The upper slabs of the roofing are ribbed concrete boards with the thickness of 50mm and in the shape of quadratic parabola, while the lower slabs are ribbed pre-stressed reinforced-concrete boards with the thickness of 40mm. The upper boards and the lower boards are combined with 9 pieces of clapboards of 40mm or 60mm-thick. The manufacturing procedures of the arch board is as the following: formwork of the upper and lower slabs, erection of the pre-casted KB boards, tensioning reinforcements of the upper slabs, and casting the upper and lower slabs on site.According to the design requirements, a pioneer static loaded test must be performed to ensure the construction quality and safety before mass production. The procedures of the static loaded test on pre-stressed concrete arch board roofing will be introduced in detail in this essay. From arranging pre-stressed steel bars to hoisting and testing on the bearer, the whole procedure was inspected and controlled by strain gauges. Meanwhile, stress of the members and their displacements during the test were compared with the data from theoretical calculation by Midas-Civil to evaluate the comprehensive construction quality and stress status after considering the actual conditions of the construction site. According to the test results, pre-stressed concrete arch boards not only proved to be beautiful and practical, but also reasonable in construction designing. The non-pre-stressed reinforced concrete and pre-stressed concrete were combined together and worked in full use. Reasons on the defects of arch board roofing found during the test and advices of further development will also be provided in this essay.