Reliability of reinforced concrete beams designed in accordance with Brazilian code NBR-6118:2014

Abstract

This paper aims to evaluate the reliability indexes of reinforced concrete beams designed in accordance with brazilian code NBR-6118:2014 in relation to the ultimate limit state of flexure. The main statistics of the resistance model are obtained through Monte Carlo simulation using ANSYS software and its probabilistic design tool. The reliability indexes are evaluated by FORM, being performed a parametric study in order to assess the influence of the main design variables on the safety level reached. It can be noticed that the reliability indexes are shown unsatisfactory in the combinations which the live loads are predominant.

Evaluation of the reliability of optimized reinforced concrete beams

“…where 𝜃𝜃 𝑅𝑅 is the resistance model error; 𝜃𝜃 𝑆𝑆 is the load model error; 𝑔𝑔 is the dead load; 𝑞𝑞 is the live load; 𝑓𝑓 𝑐𝑐 is the compressive strength of concrete and 𝑓𝑓 𝑦𝑦 is yield strength of the steel reinforcement. The statistical characteristics of the random variables (probability distribution, mean and standard deviation) are found in Table 2 and were extracted from Scherer et al [12]. The ultimate limit state considered is related to flexion, being calculated according to Equation 23, by the difference between resistance and load effects.…”

“…The random variables 𝜃𝜃 𝑅𝑅 , 𝜃𝜃 𝑆𝑆 , 𝑔𝑔, 𝑞𝑞, 𝑓𝑓 𝑐𝑐 and 𝑓𝑓 𝑦𝑦 are parameters that have uncertainties and were considered in other reliability research of reinforced concrete beams [10]- [12]. The variability of 𝜃𝜃 𝑅𝑅 is due to the approximations of the resistance calculation model, in this case being the model of NBR 6118 [15].…”

“…Several studies were carried out to optimize reinforced concrete beams [5]- [9], with different formulations and methods, but without evaluating reliability. In studies of structural reliability of reinforced concrete beams, the reliability index was evaluated in some design situations [10]- [12]. Other studies presented calibration procedures, based on reliability, of the partial safety factors of technical codes [13].…”

Comparison of two FORM methodologies for reinforced concrete beams under flexure

“…Additional comparisons between the proposed numerical model and experimental results can be found in the work of Scherer et al (2019).…”

Distribution of load effects and reliability of reinforced concrete frames: intact and with columns removed

“…This may be a consequence of the usual design procedures, where elements are designed on an element-by-element basis. Focusing on results published in Brazil, studies on the reliability of "detached" beam elements include [18]- [23] and "detached" columns include [24]- [29]. Studies addressing "detached" beams and/or columns, based on Brazil and elsewhere, include [30]- [32].…”