Analysis of the Shear Capacity of Ultrahigh Performance Concrete Beams Based on the Modified Compression Field Theory

An analysis model of the shear capacity of prestressed ultrahigh performance concrete (UHPC) beams under the combined action of bending and shearing was established in this paper based on the modified compression field theory and by considering the unique material constitutive relation of UHPC. Shear tests were performed using three prestressed UHPC-T beams with different shear-span ratios to verify the correctness of the model. The results showed that the shear-span ratio greatly influenced the shear capacity and failure modes of UHPC-T beams. Upon increasing the shear-span ratio, the failure modes of the three beams were inclined compression failure, shear compression failure, and diagonal tension failure, successively. When the shear-span ratio changed from 1.04 to 2.12, the shear bearing capacity decreased greatly; however, when the shear-span ratio changed from 2.12 to 3.19, the decrease of the shear bearing capacity was very small. In addition, the MCFT analysis model was used to analyze the experimental data, and the predicted results were in good agreement, which proved the applicability of the model. Finally, according to the existing shear test results of UHPC beams and based on the main influencing factors, a simplified formula for predicting the shear capacity of UHPC beams was obtained by fitting. Comparing the MCFT model with the results of other pieces of literature, this formula accurately predicted the shear capacity of UHPC beams. The MCFT model and the simplified formula presented in this paper provide a powerful tool for predicting the shear performance of UHPC-T beams, which will contribute to the design and analysis of UHPC-T beams.

Prediction of perforation velocity of hard missile impacts on reinforced concrete wall panels

This study reviews and compares the most commonly used models for computing the local effects of hard missile impacts. The accuracies of the models in predicting perforation velocity are evaluated using a dataset of 95 impact tests collected from the literature. It is found that the majority of the models are unable to accurately predict perforation velocity or have a limited application range because of their empirical nature. To address these limitations, a semi-analytical model based on the Modified Compression Field Theory and the principle of work and energy is proposed. Unlike most existing models, the proposed model is capable of considering the influence of in-plane and shear reinforcement. The performance of the proposed model is assessed against experimental results obtained from the compiled dataset as well as other existing models.

Nonlinear finite element analysis of reinforced concrete shear walls

ABSTRACT: This paper deals with a fundamental issue for tall buildings safety: the structural analysis of reinforced concrete shear-walls that resist lateral loads. For two shear walls (simple planar and U-shaped), the results determined according to the Brazilian design code approximate procedure (NBR-6118:2014) and the grid method (CAD/TQS), presented in the literature, are compared with material and geometrically nonlinear finite shell element analysis (NL-FEA), performed by the software VecTor 4, based on the modified compression field theory (MCFT). In both cases NL-FEA analyses, besides the large computational cost, it was observed the significant influence of stress redistribution, and the Saint-Venant’s principle, on the vertical normal stresses, and the consequent smoothing of the second order localized effects on the shear walls.

Analytical prediction of tension force on stirrups in concrete beams longitudinally reinforced with CFRP bars

An analytical study to predict the tension force of stirrups in concrete beams that are longitudinally reinforced with Carbon Fibre Reinforced Polymers (CFRP) bars was carried out. Modified Compression Field Theory (MCFT) was applied in this study and a computer program was developed to facilitate the calculation process. The analytical results were compared with empirical formula and test data adopted from experimental study. Three concrete beams longitudinally reinforced with CFRP bars and transversely reinforced with steel bars were tested. Stirrups spacing was used as test variable. The beams were tested until failure and strains on the stirrups measured. The comparison between test results and the MCFT results shows that MCFT predicts the growth of tension force in stirrups well.

Dynamic Shear Resistance of RC Beams Based on Modified Compression Field Theory

The aim of this study was to develop an analytical model to estimate the dynamic shear capacity of RC beams which may exhibit diagonal tension failure under impact and blast loadings. Thus, the modified compression field theory has been extended to dynamic loading in this study. The developed analytical model has been applied to the experimental results obtained from rapid loading tests of RC beams. As a result, the developed analytical model has been in good agreement with the experimental results.