Control of Deflection in Concrete Structures

Description

Design for serviceability is central to the work of struc-tural engineers and code-writing bodies. It is also essential tousers of the structures designed. Increased use of high-strength concrete with reinforcing bars and prestressed rein-forcement, coupled with more precise computer-aided limit-state serviceability designs, has resulted in lighter and morematerial-efficient structural elements and systems.

This inturn has necessitated better control of short-term and long-term behavior of concrete structures at service loads.This report presents consolidated treatment of initial andtime-dependent deflection of reinforced and prestressed concrete elements such as simple and continuous beams andone-way and two-way slab systems.

It presents current engi-neering practice in design for control of deformation and deflection of concrete elements and includes methodspresented in “Building Code Requirements for ReinforcedConcrete (ACI 318)” plus selected other published approachessuitable for computer use in deflection computation. Design examples are given at the end of each chapter showing how toevaluate deflection (mainly under static loading) and thuscontrol it through adequate design for serviceability.

These step-by-step examples as well as the general thrust of the report are intended for the non-seasoned practitioner who can, in a single document, be familiarized with the major state of practice approaches in buildings as well as additional condensed coverage of analytical methods suitable for computer use in deflection evaluation. The examples apply AC1 318 requirements in conjunction with PCI methods where applicable.