混凝土构件正截面受弯加固计算公式的探讨

Discussion on calculation formula for bending reinforced normal section of concrete member

国家标准《混凝土结构加固设计规范》(GB 50367—2013)于2013年11月发布、2014年6月施行,其中包含了增大截面加固法、粘贴钢板加固法、粘贴纤维复合材加固法等10种针对混凝土结构的加固方法。对受弯构件进行加固时,无论是加固前还是加固后,受弯构件的变形采用的都是平截面假定,即变形前的横截面变形后仍保持为平面,也就是欧拉-伯努利假定。受弯构件正截面承载力计算公式的本质为在平截面上同时满足力平衡和力矩平衡,建立力矩平衡方程时应根据混凝土受压区高度在不同范围采用平截面上不同的取矩点。对《混凝土结构加固设计规范》(GB 50367—2013)里的在实际工程中应用较为普遍的增大截面加固法、粘贴钢板加固法、粘贴纤维复合材加固法和预应力碳纤维复合板加固法加固受弯构件的正截面承载力计算公式进行了系统梳理,探讨了该规范中计算公式可能存在的不足,提出了具体的修订建议,可为该规范的修订提供参考。

The national standard Code for design of strengthening concrete structure(GB 50367—2013) was issued in November, 2013 and implemented in June, 2014.It includes ten reinforcement methods for concrete structures, such as structure member strengthening with increasing section area reinforcement method, pasting steel plate reinforcement method and pasting fiber composite material reinforcement method.When strengthening flexural members, whether before or after reinforcement, the deformation of flexural members adopts the plane section assumption.The cross section before deformation remains flat after deformation, that is, Euler Bernoulli assumption.The essence of the calculation formula of normal section bearing capacity of flexural members is to meet both static balance and moment balance on the plane section.When establishing the moment balance equation, different moment taking points on the plane section should be adopted in different ranges according to the height of the concrete compression zone.This paper systematically combed the calculation formulas of normal section bearing capacity of flexural members strengthened by increasing section area reinforcement method, pasting steel plate reinforcement method, pasting fiber composite material reinforcement method and prestressed carbon fiber composite plate reinforcement method, discussed the possible shortcomings of the calculation formulas in Code for design of strengthening concrete structure(GB 50367—2013),and put forward specific revision suggestions.It can provide reference for specification revision.