Advances in Civil Engineering

When the effect of combined blast induced shock wave and fragment penetration impact load is sufficiently large enough to induce severe damage in structures compared to individual actions of only-blast and only-impact load, this scenario is called synergetic effect of simultaneous actions. The combined nature of those dual actions aggravates damage and collapses of structures. This paper presented the state-of-the-art review on effect of different parameters, dynamic responses, failure types, and damage mitigation techniques for structures prone to combined actions of blast induced shock wave and fragment impact loads based on findings of experimental, numerical, and analytical research works conducted in previous literature.

To investigate the biaxial mechanical characteristics of reactive powder concrete (RPC), RPC plate specimens and bone-shaped specimens were tested under compression-compression and compression-tension loadings, respectively. The strengths and strains of the specimens were recorded, and the crack patterns and failure modes in various stress states were examined. Based on the test data, the characteristics of biaxial strength were analyzed, and a biaxial failure criterion was established. The characteristics of major stress-strain curves and failure modes in different biaxial stress states were determined. The results show that the ratio between the biaxial compression strength and the uniaxial compression strength was 1.44–1.58 for RPC. When the stress ratio under compression-tension was −0.05, the tensile strength decreased by 48%. Under compression-compression, the proportional limit of RPC was about 95%, and its peak strain was high. Under compression-tension, as the compressive stress increased, the elastic modulus decreased, and the peak strain in the tensile direction increased. When the RPC specimens were under compression-compression, the failure mode of RPC was splitting failure. Under compression-tension, the failure mode changed from single-crack tensile failure to multicrack compressive failure with increasing confining stress.

In conventional structural health monitoring (SHM), the installation of sensors and data acquisition devices will affect the regular operation of structures to a certain extent and is also expensive. In order to overcome these shortcomings, the computer vision- (CV-) based method has been introduced into SHM, and its practical applications are increasing. In this paper, CV-based SHM methods such as template matching and Hough circle transform are described. In order to improve the accuracy of pixel localization, the subpixel localization refinement method is introduced. The displacement monitoring experiment of an aluminum alloy cantilever with three targets is conducted by using the two CV-based SHM methods and the laser displacement sensors simultaneously. The displacement monitoring results of CV-based methods agree well with those measured by the laser transducer system in the time domain. After that, the first two modes of the cantilever are identified from the monitoring results. In addition, the experimental modes identified from the monitoring data and those calculated from the finite element model are also consistent. Therefore, the developed CV-based methods can obtain accurate displacement results in both time and frequency domains, which could be applied to complex structures with more monitoring targets.

This study investigates the feasibility and structural performance of textile reinforced cement (TRC) stay-in-place (SiP) formwork designed as shear reinforcement for beam-column joints under monotonic loading through the nonlinear finite element package ABAQUS. This was achieved by conducting numerical analysis on 24 beam-column joints using different parameters that affect the joints’ performance, including column axial load ratio, concrete compressive strength, beam tensile reinforcement ratio, joint shear reinforcement ratio, and thickness of TRC. The models were first calibrated to the results obtained from the experimental program of previous studies. The start of the yielding behavior of the composite beam-column (73 kN) corresponds well to the conventional beam-column joint (72 kN). A similar correlation can be observed at the ultimate load with only a 3.7% difference, 84 kN in the case of the composite beam-column joint and 81 kN in the case of the conventional beam-column joint. The findings of this investigation showed that a beam-column with a full steel stirrup and TRC SiP formwork as shear reinforcement at the joint exhibits similar yielding behavior, such that TRC SiP formwork can replace the full steel stirrup at the joint, as proved by comparison analysis. Furthermore, the numerical analysis results due to the effect of these essential parameters on the structural performance of the beam-column with TRC SiP formwork at the joint were also discussed.

The deformation property of marine clay under a heat source has received considerable attention in the geotechnical literature. In this paper, a three-parameter fractional order derivative model is introduced into the thermo-hydro-mechanical coupling governing equations with thermal filtration and thermo-osmosis to simulate viscoelastic characteristics of marine clay. The excess pore pressure, temperature increment, and displacement of marine clay are derived by using the Laplace transform method, and the semianalytical solution for the one-dimensional thermal consolidation in the time domain is derived by using a numerical inversion of the inverse Laplace transform. The influence of the order of the fractional derivative, material parameters, and phenomenological coefficient on thermal consolidation is investigated based on the present solutions. It is shown that the influence of the fractional derivative parameter on the excess pore pressure and displacement of marine clay depends on the properties of soil mass, and the temperature increment has an obvious effect on the thermal filtration and thermo-osmosis process.

This paper proposes analytical solutions to the soil deformation around a cylindrical cavity under drained conditions. Analytical procedures are used to predict the degree of interaction between cavities and ground surface loads based on mathematical theorems. The stresses applied at the boundary condition induce the ground motions around the cylindrical cavity wall. Additionally, the Airy stresses are obtained through mathematical derivatives and integrations by combining the Fourier analysis test with the Navier equations. Next, we established a schematic representation of the horizontal and vertical displacement related to the corrective shear model to obtain insight into the intensity and directions of ground stresses. The resulting transformations include displacement, shear, and deviatoric stresses applied to the cylindrical cavity wall. These data can be used as input parameters for numerical simulations to alternatively solve the groundmass redistribution problems and calibrate the horizontal stress of drained soil conditions.