Study On A New Type Of GFRP Sandwich Formwork

Formwork is the essential working tools in concrete placing. Either site-placing or prefabricated in factories concrete elements must use formworks all, so that fomwork should possess great performances, conveniencing construction, and low cost. However, some disadvantages are existing generally in presently used formworks, which caused manpower and material wastings, and unreachable anticipating economic effects. Thus investigation on the materials and conformation of formwork and developing new type of formwork meeting the Chinese situation has significant theoretical and applied values.According to analysis on existing formworks, this paper presented a new type of GFRP sandwich formwork. Based on experimental research and theoretical analysis, investigations on the new type of formwork were made systematically. The main contents and results included in the following items.1 Refering to overseas and domestic producing technologies of composite, presented the producing technology of the new type of formwork, and some influential factors, such as fiber placing, glue binding and shapping pressure were discussed. The producing technology is orientating GFRP pipes and paper honeycombs at first, and then faced with two polyester glass fiber plates. This technology can make formwork smooth and level.2 Four speciments of new formwork were desingned. By dead-load test, the strength, stiffness and the feasibility of the producing technology of the new formwork were verified. Experimental results showed that the new formwork proposed in this paper possessed sufficient strength and stiffness, and could meet the requirements for construction, in the condition of good cementation. GFRP pipes in sandwich layer could effectively minish the distortion of sandwich construction, and enhance the utilization of faceplate materials.3 Based on experimental results and finite elements analysis of new formwork, the bearing mechanism of the new sandwich structure was analyzed, and the effects of section's highness and faceplates'thickness on flexibility of formwork were discussed. Calculating outcomes displayed that GFRP pipes was formwork's control elements, and honeycomb enhanced the inertia moment of section and planar compression modul of forwork. Increasing section's highness was the more effective method in minishing formwork's flexibility than increasing faceplates'thickness, but thicker faceplates could enhance shearing strength.4 Grounding on the calculational theory of sandwich constructions, calculational methods about stress and flexibility of the sandwich construction were discussed. Then the design method of new formwork was presented. Analysis of economic effects of using new formwork showed that the new formwork has a lot of merits, such as lighter, larger, appropriate cost andso on, and possesses some spreading and applicational prospects.