In this paper, a new strengthening technique for reinforced concrete (RC) beams is proposed by combining Basalt fiber Reinforced Polymer (BFRP) grid and Engineered Cementitious Composites (ECC) as a composite reinforcement layer (CRL). Five RC beams externally bonded with the CRL at the soffit and one control RC beam were tested to investigate their flexural behaviour. The thickness of BFRP grids (i.e. 1 mm, 3 mm and 5 mm) and the bonded length of CRL (i.e. 400 mm, 450 mm and 500 mm) were selected as two main parameters in the test program, while the width and thickness of CRL were fixed approximately at 200 mm and 30 mm, respectively. The test results showed that there is no clear CRL debonding in the strengthened beams. The two final failure modes were concrete crushing or rupture of the BFRP grids, indicating that the proposed technique is effective in suppressing the debonding of externally bonded materials and fully utilizing the material strengths. An analytical model is also presented to predict the load-deflection responses of the strengthened beams, which was validated through comparisons with the test results

Based on numerical shape functions and the structural stressing state theory, the mechanical properties of the curved prestressed concrete box girder (CPCBG) bridge model under different loading cases are presented. First, the generalized strain energy density (GSED) obtained from the measured strain data is used to represent the stressing state pattern of the structure; then, the stressing state of the concrete section is analyzed by plotting the strain and stress fields of the bridge model. The stressing state pattern and strain fields of the CPCBG are shown to reveal its mechanical properties. In addition, the measured concrete strain data are interpolated by the non-sample point interpolation (NPI) method. The strain and stress fields of the bridge model have been plotted to analyze the stressing state of the concrete cross-section. The internal forces in the concrete sections are calculated by using interpolated strains. Finally, the torsional effects are simulated by measuring the displacements to show the torsional behavior of the cross-section. The analysis and comparison of the internal force and strain fields reveal the common and different mechanical properties of the bridge model. The results of the analysis of the curved bridge model provide a reference for the future rational design of bridge projects.

Explosion craters on the ground surface induced by contact or near‐field explosions have important implications, which can be used to assess blast consequences, guide the design of the explosion, or develop a protective strategy. In this study, to understand the crater characteristics induced by the contact explosion of large weight explosives, four field contact explosion tests were conducted on the surface of the Gobi Desert with large TNT charge weights of 1 ton, 3 tons, and 10 tons (test conducted twice). Cratering on the ground surface generated by large amounts of explosives was measured and evaluated, including the shape, depth, and diameter. A fine‐mesh numerical model was developed and validated on the AUTODYN software platform, and a detailed parametric study was performed on the resulting craters. The effects of sand and gravel density, initiation method, shear modulus, and failure criteria were analyzed and discussed. An energy conversion coefficient was determined, and the corresponding theoretical equations were derived to predict the dimensions of the craters resulting from the large weight contact explosion. The calculated cratering characteristics were consistent with previous data and hence can be used in future engineering applications.

The bending behavior of reinforced concrete beams under uniform pressure is critical for the research of the blast-resistance performance of structural components under explosive loads. In this study, a bending test of five reinforced concrete beams with the dimensions of 200 mm (width) × 200 mm (depth) × 2500 mm (length) under uniform load produced by a specific cylinder-shaped rubber bag filled with air or water was conducted to investigate their flexural performances. An air bag load was applied to three of the reinforced concrete beams, a water bag load was applied to one reinforced concrete beam, and the remainder beam was subjected to the 4-point bending load. The experimental results highlighted that the air bag and water bag loading methods can be used to effectively apply uniform loads to reinforced concrete beams. Moreover, the stiffness of the air bag was improved by 123% in accordance with the initial pressure increases from 0.15 to 0.45 MPa. In addition, a finite element model of the test loading system was established using ABAQUS/Standard software. Moreover, the critical factors of the air bag loading method were analyzed using the numerical model. The calculated results were found to be in good agreement with the test data. The established finite element model can therefore be used to accurately simulate the action performances of the uniform loading technique using rubber bags filled with air or water.

To explore the influence of microexpansive concrete self‐stress on the performance of steel pipe concrete, the expansion rate test of microexpansive concrete confined by steel tube was carried out with different expansion rates. Then, the mechanical properties of high‐strength steel tube‐confined microexpansive concrete (HSTCMC) short columns were conducted by the uniaxial compression test. The length‐to‐diameter ratio, the expansion rate of the microexpansive concrete, and the steel tube thickness were investigated in the study. Furthermore, the ABAQUS software was employed to analyze the microexpansive mechanism of the concrete, and it was verified by the uniaxial compression test. The test results show that the concrete possesses a remarkable volume expansion phenomenon, which was up to 150 με after four days of maintenance time. The mechanical properties of the HSTCMC short columns were greatly improved compared to the control RC pier. The yield and ultimate strength of the HSTCMC short columns can be enhanced to 8.9% and 14.6%, and with the content of expansive agent that increased from 8% to 12%. The finite element analysis results highlighted that the end constraint at the two ends has the biggest influence on the mechanical performance of the HSTCMC short columns, followed by the thickness of the steel tube and the content of the expansive agent. It should be noted that the self‐stress of microexpansive concrete will be decreased with the increase in the length‐to‐diameter ratio, when the length‐to‐diameter ratio is less than four. Furthermore, the constraint effect of the circular steel tube on the microexpansive concrete is better than that of the rectangular section steel tube.