论文部分内容阅读
确定预应力钢丝的传力长度对正确核算先张法预应力构件瑞部的抗裂强度和抗切强度有重要的意义。预应力钢丝的端部回缩量与其传力长度有着一定的关系,即著名的居容(Y.Guyon)公式[12]l_a=λE_a/σ_0g_0。借测定瑞部回缩量,用居容公式来计算预应力钢丝的传力长度,非常方便。运用该公式的主要困难在于系数λ不是一个常数;根据已有的资料,它随钢筋品种、预应力大小、混凝土强度等因素而在1.8至4.8之间变动。本文用图解分析法论证了统一λ系数的可能性及由此而引起的误差大小。确定当系数统一成λ=2.5以后,由公式算出的传力长度内及真实的传力长度内最大预应力值的差误不大于10%。在统一系数λ的基础上,居容公式将被成功地应用到生产实践中去测定预应力钢丝的传力长度以控制预应力混凝土构件的生产质量。
Determining the length of the transmission force of the prestressed steel wire is of great significance for the correct calculation of the cracking strength and shear strength of the pre-tensioned prestressed member. The amount of retraction of the end of the prestressed steel wire has a certain relationship with the length of the transmission force, namely the famous Y. Guyon formula [12] l_a = λE_a/σ_0g_0. It is very convenient to determine the force transmission length of the prestressed steel wire by using the formula of volumetric capacitance by measuring the amount of withdrawal in the Rui. The main difficulty in using this formula is that the coefficient λ is not a constant; based on available data, it varies from 1.8 to 4.8 with factors such as the type of reinforcement, prestress, and concrete strength. In this paper, graphical analysis is used to demonstrate the possibility of uniform lambda coefficient and the resulting error. It is determined that when the coefficient is unified into λ = 2.5, the maximum pre-stress value error within the transmission force length calculated by the formula and the actual force transmission length is not greater than 10%. On the basis of the unified coefficient λ, the formula of the volumetric capacity will be successfully applied to the production practice to determine the force transmission length of the prestressed steel wire to control the production quality of the prestressed concrete component.