Reliability Analysis of Nano Engineered Reinforced Concrete Beam

Abstract

This work presents reliability analysis of Nano Engineered Reinforced Concrete (NERC) beam designed according to EN1992-1-1(2008) and its reference standard. In the reliability analysis, variability in load, geometric properties, Optimal Nano Engineered Concrete (ONEC) grade and other design variables were considered. The reliability analysis utilized FORM (First Order Reliability Method) with FORTRAN subroutine programs developed for the NERC beam failure modes at ultimate limit state. Results indicated that NERC beam behaves in a similar manner to conventional reinforced concrete beam on strength aspect. At design point, the NERC beam failed to meet the target safety index values provided by EN1990: 2002 (EC0) as a reference standard of EN1992-1-1 (2008) for all the failure modes considered. Furthermore, variations in span and reinforcement ratio have been found to be capable of changing the criticality of failure modes of NERC beam. Also, variation in characteristic yield strength of steel was found to severely affect NERC beam safety. This study recommends that unnecessary variation of span, reinforcement ratio and characteristic yield strength of steel should be avoided in NERC beams at project implementation stage so as to reduce the possibility of unforeseen structural failures. The work suggested that the safety margin provided by EN1992-1-1 (2008) and its reference standards for the design of singly reinforced concrete sections without shear reinforcement be improved. Finally, the study observed the need for incorporation of reliability-based design in Civil Engineering design standards.