本文介绍《程规》第三章及第四章第一节的内容,主要涉及无粘结预应力筋的应用,在结构设计与施工中的一些基本的规定,如荷载效应组合,无粘结预应力筋损失值计算、防火及防腐蚀规定、跨高比限值、裂缝控制与裂缝验算、无粘结预应力筋设计应力取值、对施工的一般要求和减少支承结构约束的措施等。现分述如下。 一、无粘结预应力楼盖体系 常用的后张楼盖体系如图1所示。单向板(图1a)在荷载作用下,主要沿一个方向出现弯曲变形,故按梁进行设计。单向板常用跨度为6～9m,跨高比约为45。对跨度往7～12m,活荷载在5kN/m~2 This article introduces the contents of Chapter 3 and Chapter 1 of the “Schedule” and mainly deals with the application of unbonded prestressed tendons, some basic rules in the design and construction of structures, such as the combination of load effects and non-adhesion. Calculation of loss value of prestressed tendons, fire prevention and anti-corrosion regulations, limit value of span-to-height ratio, calculation of crack control and cracks, design stress of unbonded prestressed tendons, general requirements for construction and measures to reduce restraint of support structures, etc. The breakdown is as follows. First, non-bonded prestressed floor system The commonly used post-tensioned floor system is shown in Figure 1. The unidirectional plate (Fig. 1a) undergoes bending deformation mainly in one direction under the action of the load, so it is designed according to the beam. The common span of the one-way plate is 6~9m, and the span-to-height ratio is about 45. For the span to 7 to 12m, the live load is 5kN/m~2