This paper numerically studied the effect of uncertainty and random distribution of concrete strength in beams failing in shear and flexure using lattice modeling,which is suitable for statistical analysis.The indepen...This paper numerically studied the effect of uncertainty and random distribution of concrete strength in beams failing in shear and flexure using lattice modeling,which is suitable for statistical analysis.The independent variables of this study included the level of strength reduction and the number of members with reduced strength.Three levels of material deficiency(i.e.,10%,20%,30%)were randomly introduced to 5%,10%,15%,and 20%of members.To provide a database and reliable results,1000 analyses were carried out(a total of 24000 analyses)using the MATLAB software for each combination.Comparative studies were conducted for both shear-and flexure-deficit beams under four-point loading and results were compared using finite element software where relevant.Capability of lattice modeling was highlighted as an efficient tool to account for uncertainty in statistical studies.Results showed that the number of deficient members had a more significant effect on beam capacity compared to the level of strength deficiency.The scatter of random load-capacities was higher in flexure(range:0.680-0.990)than that of shear(range:0.795-0.996).Finally,nonlinear regression relationships were established with coefficient of correlation values(R^(2))above 0.90,which captured the overall load-deflection response and level of load reduction.展开更多
This study presents experimental and numerical investigations on the mechanical properties of ultrahigh-performance concrete(UHPC)reinforced with single and hybrid micro-and macro-steel and polypropylene fibers.For th...This study presents experimental and numerical investigations on the mechanical properties of ultrahigh-performance concrete(UHPC)reinforced with single and hybrid micro-and macro-steel and polypropylene fibers.For this purpose,a series of cubic,cylindrical,dog-bone,and prismatic beam specimens(total fiber by volume=1%,and 2%)were tested under compressive,tensile,and flexural loadings.A method,namely multi-target digital image correlation(MT-DIC)was used to monitor the displacement and deflection values.The obtained experimental data were subsequently used to discuss influential parameters,i.e.,flexural strength,tensile strength,size effect,etc.Numerical analyses were also carried out using finite element software to account for the sensitivity of different parameters.Furthermore,nonlinear regression analyses were conducted to obtain the flexural load-deflection curves.The results showed that the MT-DIC method was capable of estimating the tensile and flexural responses as well as the location of the crack with high accuracy.In addition,the regression analyses showed excellent consistency with the experimental results,with correlation coefficients close to unity.Furthermore,size-effect modeling revealed that modified Bazant theory yielded the best estimation of the size-effect phenomenon compared to other models.展开更多
文摘This paper numerically studied the effect of uncertainty and random distribution of concrete strength in beams failing in shear and flexure using lattice modeling,which is suitable for statistical analysis.The independent variables of this study included the level of strength reduction and the number of members with reduced strength.Three levels of material deficiency(i.e.,10%,20%,30%)were randomly introduced to 5%,10%,15%,and 20%of members.To provide a database and reliable results,1000 analyses were carried out(a total of 24000 analyses)using the MATLAB software for each combination.Comparative studies were conducted for both shear-and flexure-deficit beams under four-point loading and results were compared using finite element software where relevant.Capability of lattice modeling was highlighted as an efficient tool to account for uncertainty in statistical studies.Results showed that the number of deficient members had a more significant effect on beam capacity compared to the level of strength deficiency.The scatter of random load-capacities was higher in flexure(range:0.680-0.990)than that of shear(range:0.795-0.996).Finally,nonlinear regression relationships were established with coefficient of correlation values(R^(2))above 0.90,which captured the overall load-deflection response and level of load reduction.
文摘This study presents experimental and numerical investigations on the mechanical properties of ultrahigh-performance concrete(UHPC)reinforced with single and hybrid micro-and macro-steel and polypropylene fibers.For this purpose,a series of cubic,cylindrical,dog-bone,and prismatic beam specimens(total fiber by volume=1%,and 2%)were tested under compressive,tensile,and flexural loadings.A method,namely multi-target digital image correlation(MT-DIC)was used to monitor the displacement and deflection values.The obtained experimental data were subsequently used to discuss influential parameters,i.e.,flexural strength,tensile strength,size effect,etc.Numerical analyses were also carried out using finite element software to account for the sensitivity of different parameters.Furthermore,nonlinear regression analyses were conducted to obtain the flexural load-deflection curves.The results showed that the MT-DIC method was capable of estimating the tensile and flexural responses as well as the location of the crack with high accuracy.In addition,the regression analyses showed excellent consistency with the experimental results,with correlation coefficients close to unity.Furthermore,size-effect modeling revealed that modified Bazant theory yielded the best estimation of the size-effect phenomenon compared to other models.
