Details about beam deflection

In civil engineering terms, Deflection means the transition of a beam or node from its primary position because of the forces and loads which are employed to the member.

Deflection is also called as displacement and it can happen from exterior applied loads or from the weight of the structure itself as well as the force of gravity in which it is used. It can happen in beams, trusses, frames and mainly any other structure.

There are two types of deflections like short and long-term deflections.

Short term deflection belongs to the immediate deflection once the casting is completed and partial or full service loads are employed.

Long term deflection happens over a long period of time mostly because of shrinkage & creep of the material.

Short term deflections are affected by the factors given below :-

1) Magnitude and distribution of live loads
2) Span and type of end supports
3) Cross-sectional area of the members
4) Steel reinforcement amount and the stress induced in the reinforcement
5) Characteristics strengths of concrete and steel
6) Amount and span of cracking

Long term deflections are affected by the factors given below :-

1) Humidity and temperature spread throughout curing
2) Age of concrete in the course of loading
3) Type and size of aggregates, water-cement ratio, amount of compression reinforcement, size of members etc., which affect the creep and shrinkage of concrete

In this regard, an exclusive video tutorial is presented by Prof. S.K. Bhattacharyya, dept. of civil engineering, IIT Kharagpur.

Video Source: nptelhrd