Prestressed Concrete Design, 1/e

Chapter 8

Deflections

8.1 Introduction

Predicting the deflections is necessary to check the performance of flexural members at serviceability limit state. Since prestressed concrete members are slender than reinforced concrete members, check for deflection becomes more important. Deflection in a prestressed concrete member is usually checked at transfer (short term deflection) and at service condition (long term deflection).

At transfer, the member is subjected to prestressing force and the self-weight of member, usually resulting in an upward deflection (also known as camber). The amount of camber should be controlled in roof slabs to avoid drainage problems. Also in projects involving precast members, excessive camber will cause difficulty ...