The behavior at the interface between normal strength concrete (NSC) and Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) plays a crucial role in accurately predicting the capacity of UHPFRC for strengthening and repairing concrete structures. Until now, there has been a lack of sufficient finite element (FE) models for accurately predicting the behavior at the interface between NSC and UHPFRC. This study aims to investigate the structural behavior of composite members made of NSC and UHPFRC by developing a model that accurately simulates the interface between the two materials using a linear traction-separation law. Novel parameters for the surface-based cohesive model, based on the traction-separation model, were obtained and calibrated from prior experiments using analytical methods. These parameters were then integrated into seven FE models to simulate the behavior at the interface between NSC and UHPFRC in shear, tensile, and flexural tests. The accuracy of the FE models was validated using experimental data. The findings revealed that the proposed FE models could effectively predict the structural behavior of composite NSC-UHPFRC members under various working conditions. Specifically, the maximum deviations between EXP and FEA were 6.8% in ultimate load for the shear test and 15.9% and 2.8% in ultimate displacement for the tensile and flexural tests, respectively. The model can be utilized to design the use of UHPFRC and ultra-high performance fiber-reinforced shotcrete (UHPFRS) for repairing and strengthening damaged concrete structures.

Crack patterns provide critical information about the structural integrity and safety of concrete structures. However, until now, there has been a lack of sufficient studies on using the Finite Element (FE) method to investigate the characteristics of the crack patterns of reinforced concrete (RC) beams. Therefore, this study aims to develop an FE model to analyze the load–displacement and crack characteristics of a beam under a four-point bending test using the concrete damaged plasticity (CDP) model that accounts for the influence of mesh size. The simulation results were validated against experimental results, including mesh convergence analysis, energy balance, load characteristics, and crack patterns. A parametric study was then conducted using this model to investigate the influence of the rebar’s diameter, number, and spacing on the RC beam’s load–displacement characteristics and crack behavior. The findings demonstrate that the FE model accurately simulates the working behavior of the RC beam, with a maximum deviation at a cracking load of 8.7% and crack patterns with a maximum deviation in the mean crack height of 12.1%. In addition, the results of the parametric study suggest that the rebar configuration significantly affects the RC beam’s loading carrying capacity. This study provides deeper insights into the use of FE modeling for analyzing the behavior of RC beams, which can be useful for designing and optimizing structures in civil engineering.

In the last few decades, fires caused serious damage in civil engineering, especially in the high-rise building, factories, offices, etc. Usually the structures are built with fireproof materials such as concrete. It is a complex material, and its properties can change dramatically when exposed to high temperatures. This problem requires engineers to study and evaluate the effect of the fire in the structure. This paper studies the effect of the fire on the temperature distribution in concrete structure using Finite Element Ansys software. The results will be used to provide reference data for concrete structures under the action of fire. The research is an intermediate task to convert the fire activity in a structural model into the real impact in calculating model. It plays significant role in calculating structural model for counteracting the action of fire.

Most of the structures that are damaged by an explosion are not initially designed to resist this kind of load. In the overall structure of any building, columns play an important role to prevent the collapse of frame structure under blast impact. Hence, the main concept in the blast resistance design of the structure is to improve the blast load capacity of the column. In this study, dynamic analysis and numerical model of Ultra High Performance Concrete (UHPC) column under high explosive load, is presented. Based on the Johnson Holmquist 2 damage model and the subroutine in the ABAQUS platform, a total of twenty UHPC model of the column were calculated. The objective of the article is to investigate the structural response of the UHPC column and locate the most vulnerable scenarios to propose necessary recommendations for the UHPC column in the blast loading resistance design. The input parameters, including the effect of various shapes of cross-section, scaled distance, steel reinforcement ratio, and cross-section area, are analyzed to clarify the dynamic behavior of the UHPC column subjected to blast loading. Details of the numerical data, and the discussion on the important obtained results, are also provided in this paper.