免支撑UHPC模板抗弯性能试验研究与分析

Experimental Study on the Bending Performance of Unsupported UHPC Formwork

摘要: 为了解决普通叠合板模板易开裂、需设大量临时支撑的难题，研发了一种免支撑钢筋桁架UHPC模板，通过对3块免支撑钢筋桁架UHPC模板和3块UHPC模板进行静力加载试验，分析有无设置钢筋桁架的UHPC模板的破坏形态、承载力、挠度变化以及荷载–应变关系。研究表明：两种模板均基本遵循平截面假定，由于钢筋桁架显著提高了模板的抵抗矩，使钢筋桁架UHPC模板相较UHPC模板刚度和抗裂性能显著增加，且在免支撑条件下UHPC模板和钢筋桁架UHPC模板分别最大可承受均布荷载为规范设计值的1.54、1.70倍。基于应力等效假定，推导出钢筋桁架UHPC模板的开裂承载力计算式，其计算值与实测值吻合良好。经计算，在模板厚60 mm的条件下，免支撑跨度可达3.29 m，应用场景广泛。

Abstract: To address the challenges of cracking and extensive temporary support requirements in conventional composite slab formwork, a support-free steel truss UHPC formwork system has been developed. Static loading tests were conducted on three support-free steel truss UHPC formwork panels and three conventional UHPC formwork panels. The tests analysed the failure patterns, load-bearing capacity, deflection changes, and load-strain relationships of UHPC formwork with and without steel trusses. The research indicates that both formwork types fundamentally adhere to the flat-section assumption. The reinforcement truss significantly enhances the formwork’s moment of resistance, markedly increasing the stiffness and crack resistance of the truss-reinforced UHPC formwork compared to the standard UHPC formwork. Under unsupported conditions, the UHPC formwork and truss-reinforced UHPC formwork can withstand uniformly distributed loads of up to 1.54 times and 1.70 times the code design value, respectively. Based on the stress equivalence assumption, a cracking load-bearing capacity calculation formula for the steel truss UHPC formwork was derived, with calculated values showing good agreement with measured data. Calculations indicate that under a formwork thickness of 60 mm, the unsupported span can reach 3.29 m, offering broad application potential.