ALL STRUCTURES MAY BE ANALYSED TO CALCULATE INTERNAL ACTIONS PRODUCED BY THE DESIGN LOADS.

The safety and serviceability of the structure is required for throughout the life and use of the structure , as such structure shall be designed to withstand safely, all loads liable to act on it and it shall also satisfy the serviceability requirements, such as limitations on deflection and cracking. The acceptable limit for the safety and serviceability requirements before failure occurs is called a limit state , as such the aim and objective of the design is to achieve acceptable probabilities that the structure will not become unfit for the use for which it is intended, that is, that it will not reach a "Limit State".For ensuring the above objective, the design should be based on characteristic values for strength of the materials and the applied loads, which take into account the variations in the material strengths and in the loads to be supported, The characteristic values should be based on the statstical data if available and where such data are not available they should be based on experience after verification of the site of work and the design values are derived from the characteristic values through the use of partial safety factors, one for the strength of material and the other for the loads. The term characteristic strength means that value of the strength of the material below which not more than five percent of the test results are expected to fall. The term characteristic load means that value of load which has a 95 percent probability of not being exceeded during the life of the structure. Methods of analysis shall be used and the material strength to be assumed shall be charecrestic values in the determination of elastic properties of members irrespective of the limit state being considered.