Probabilistic analysis of shear fatigue life of steel plate girders of two railway bridges with welded connections, designed according to Indian Railway Standards, is presented in this paper. The fatigue life is determined using a fracture mechanics based procedure. Deterministic and probabilistic sensitivity analyses are carried out and, based on the results of these sensitivity analyses, the random variables having significant influence on fatigue life are identified. The probability distribution of fatigue life is determined using the Monte Carlo simulation technique and a relation for estimating the characteristic fatigue life is proposed.

The present study presents the effects of steel fibre aspect ratio on the fresh and strength properties of self-consolidating concrete (SCC). Steel fibre having three different aspect ratios (50, 65 and 80) with the inclusion rate of 0.2%, 0.4%, 0.6%, 0.8%, and 1.0% was considered, and the effects of aspect ratio and the fibre inclusion rate on the fresh and strength properties of SCC were investigated. Central composite design (CCD) of RSM modeling was considered to propose a regression model to predict the 28-day compressive strength of SCC and steel fibre-reinforced SCC (SFSCC) incorporating different supplementary cementitious materials (SCMs). 94 data sets retrieved from various literatures and the experimental data set (SCC and SFSCC) of this present study have been used to develop the regression model. Further, cement content, powder content, water to binder ratio, and coarse aggregate to fine aggregate ratio were considered as basic variables to propose the model, and their influence on the strength properties of SCC was prioritized using analysis of variance (ANOVA) and Pareto chart. The findings of regression model have been compared with the results of 94 data sets, and the experimental data set of this present study and the comparisons confirm that the proposed regression model are very realistic and precise to predict the compressive strength of SCC and SFSCC with different aspect ratio.

This paper presents the findings of investigation, which was instigated to assess the effects of fibre aspect-ratio on the fresh and mechanical properties of SCC. The investigational parameters were aspect-ratio of the fibre and fibre addition rate. Two different aspect-ratios (64 and 73) of steel fibre were used and the fibre addition rate was between 0.2% and 1.0% with the increment of 0.2% and the fibres were added to the SCC in volume fraction. A series of tests were performed to determine the impact of fibre aspect-ratio and fibre inclusion rate on the engineering/mechanical properties of SCC. The presence of steel fibre in the SCC lessened the workability; furthermore, the upsurge in the inclusion rate of steel fibre abridged the workability further. The inclusion of fibre boosted the compressive strength of the SCC moderately, and conversely, an overwhelming increase in flexural and tensile strength was observed. The rise in the fibre aspect-ratio caused a 2.53% augmentation in the compressive strength of the SCC. Nevertheless, more than 11% improvement in tensile strength was observed, because of the bridging/anchorage established by the fibre. From the obtained results, it can be inferred that the impact of fibre aspect-ratio on the compressive strength of the SCC is not substantial; however, the tensile strength properties of the SCC can be enhanced moderately by increasing the fibre aspect-ratio.

The structural behaviour of concrete-filled steel tubular columns subjected to full and local compression loads was investigated. Experiments were performed on 18 columns with different cross-sectional slenderness ratios. The experimental parameters were the local compression area ratio and the slenderness ratio. The strength index, stiffness and ductility index of the columns were obtained through experimental tests. The results revealed that the local compression area ratio and slenderness ratio are key parameters that considerably affect the strength capacity of columns subjected to full and local compression loads. Design models provided in various international codes and various studies were used to validate the experimental results. Furthermore, the suitability of these design models for predicting the strength capacity of columns subjected to full and local compression loads was examined. Finally, through regression analysis, a simplified design model was developed for predicting the strength capacity of columns under full and local compression loads.

The impacts of three diameter/thickness (D/t) ratios (21.22, 25.46, and 31.83) and concrete strengths (40 N/mm2, 50 N/mm2, and 60 N/mm2) on the strength capabilities of concrete-filled steel tubular (CFST) columns are investigated in this study. The central composite design (CCD) of the response surface methodology (RSM) was used to design the trials in order to complete the tests in a cost-effective manner. 13 (9 distinct tests) columns were evaluated according to the CCD experimental design, and the failure mode of the specimens, load–deformation behavior, and ultimate strength capacity were investigated. Concrete strength improves, resulting in a decrease in steel tube confinement on the core. Because the steel tube longitudinal compressive stress (fsl) increases as the D/t ratio lowers, the confinement is reduced by inhibiting the circumferential tensile stress (fsc). The Reynolds stress model’s, analysis of variance (ANOVA), Pareto chart, and contour plot demonstrated that the column D/t ratio, rather than the in-filled concrete strength, has a considerable impact on the CFST column’s strength capability. The proposed design models in different international codes and literature were evaluated for their effectiveness in predicting the strength capacities of CFST columns subjected to axial compression load. Using regression analysis, a simple design model was suggested to predict the axial strength capacities of CFST short columns, taking into account material strength and column shape. In comparison to other existing and suggested design models, the proposed design model of the present study delivers a more accurate and stable forecast.