Incorporated Strength Capacity Technique for Limit Load Evaluation of Trusses and Framed Structures under Constant Loading

To overcome the difficulties encountered by the elastic modulus adjustment procedures applied to the ultimate bearing capacity analysis of framed structures under combined action of both constant and varying live loads, an efficient incorporated strength capacity technique is proposed in this work. A new structural analysis model is developed with totally different distributions of loads and resistance from the original model by incorporating the constant load effects into the sectional strength capacity of components in framed structures. The element bearing ratio (EBR) is defined according to the modified structural model on the basis of the generalized yield function of spatial beam element. The uniformity of the EBR is presented in terms of the EBR distribution characteristics, on the basis of which the reference EBR (REBR) is defined as a dynamic threshold to identify the highly stressed elements with the EBR greater than the REBR. Subsequently, an adaptive strategy of elastic modulus adjustment is presented for the ultimate bearing capacity analysis of framed structures under combined action of constant and live loading by means of the principle of deformation energy conservation. Three numerical examples including both trusses and framed structures are presented to demonstrate the applicability and accuracy of the proposed methodology. (C) 2015 American Society of Civil Engineers.