Comparative analysis of design models for concrete corbels

Abstract

ResumoThe main objective of this paper is performing a comparative analysis of some design models for precast concrete corbels. For this, it was analyzed design models from Brazilian (NBR 9062) and European (EUROCODE 2) Codes and a US design handbook (PCI). Moreover, three analytical models showed in the literature are analyzed. The objective of this comparative is identifying the best design models to represent the failure load of concrete corbels by the tie yields or by the concrete crushing. Moreover, it is intended to evaluate the contribution of horizontal stirrups to resistance of concrete corbels. For this, a database was assembled from test results of concrete corbels carried out by several researchers and they are showed in the literature. The design models were applied to this database and from statistical tools, adjustments coefficients are recommended to be applied on these design models to take into account the results dispersion found in the analysis.Keywords: corbels, precast concrete, design models, horizontal stirrup.O objetivo deste trabalho é realizar uma análise comparativa de alguns modelos de cálculo para consolos de concreto pré-moldado. Para isso, são analisados os modelos de cálculo das normas brasileiras (NBR 9062) e europeia (EUROCODE 2) e de um manual de projeto norte-americano (PCI). Além disso, são analisados três modelos de cálculo sugeridos na literatura. Busca-se nessa comparação identificar os modelos que melhor representam a força de ruína dos consolos, seja pelo escoamento do tirante ou pelo esmagamento do concreto da biela. Além disso, busca-se identificar a contribuição da armadura de costura na resistência do consolo. Para isso, foi montado um banco de dados a partir de resultados de ensaios de consolos de concreto realizados por diversos pesquisadores presentes na literatura, no qual os modelos em questão foram aplicados. Utilizando-se de ferramentas estatísticas, são definidos coeficientes de ajustes a serem aplicados aos modelos para uso em projeto e que levam em conta a dispersão de resultados encontrada na análise.Palavras-chave: consolos, concreto pré-moldado, modelos de cálculo, armadura de costura.

Numerical Analysis of Reinforced Concrete Corbels Using Concrete Damage Plasticity: Sensitivity to Material Parameters and Comparison with Analytical Models

“…The PCI model was the one that came closest to the experimental results, with an average analytical ultimate load/experimental ultimate load of 1.62 (V u,ana /V u,exp = 1.62), which represents an average error of 62%. In general, all analytical models overestimate the corbel strength and present a high coefficient of variation, between 26.73% and 40.52%, which is in line with the results found by Araújo et al [14]. When comparing the numerical and analytical results, it is possible to highlight the potential of the numerical model in predicting the results, as an average numerical ultimate load/experimental ultimate load of 1.04 was obtained (V u,num /V u,exp = 1.04) and coefficient variation of only 10.94% when using a dilatancy of 48 • .…”

“…In this item, analytical results of compression strut strength are obtained using the strut and tie models of ABNT NBR 9062:2017 [1], PCI [2] and EN 1992-1-1:2004 [3]. The deduction of the equations used is available in the study by Araújo et al [14]. As one of the purposes is to evaluate the ability of the analytical models to predict the real strength of the corbel, no safety coefficient will be used, and mean values of material properties were considered instead of characteristic values.…”

“…Araújo et al [14] analytically compared a database with 62 short concrete corbels using normative models [1-3] and observed low accuracy of the analytical models in predicting the experimental failure strength, with an average ratio V u.exp /V u,ana between 0.83 and 1.30 and a high coefficient of variation (COV) between 31% and 59%. One of the explanations for these results is that corbels are elements from region D. According to Szczecina and Winnicki [15], elements from region D represent a region of stress discontinuity, where the distribution of deformations is not linear.…”

Bearing capacity calculation of reinforced concrete corbels under the shear action

“…Research articles [1][2][3][4] are devoted to the strength problem of reinforced concrete corbels. The ultimate stress-strain state is investigated, experimental data are presented and their calculation methods analysis is performed in these articles.…”