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In this paper, a bolted joint of two prismatic parts subjected to a shear impact force applied in the structure’s longitudinal direction is studied. The base part is made from steel and the connected one is from aluminum alloy. An elastomeric layer is inserted between the assembled parts in order to reduce vibration resulting from external excitation. An equivalent dynamic model is developed to analyze the behavior of bolted structure. The formulation of the problem gives a system of nonlinear equations. Solving differential equations is based on Euler’s method. Dynamic responses which correspond to the two degrees of freedom of the model are shown. The joint nonlinear behavior strongly depends on the interface properties. A cubic stiffness and damping factor are considered for the layer in the model, which gives it more realistic responses. Experimental tests are done for a case study of bolted joint under transient hummer impact. Model results are agreed with those issued from experiments. The damping layer (DL) effect is experimentally observed as well as in the model results.

The classic plate theory (CPT) as a theoretical solution to an impact load has been used in a thin plate. However, The CPT is not any more useful solution for the impact load in the industrial power plant, which is generally constructed by the thick plate. In this paper a novel and effective approach is developed to determine the time history of the impact load on a thick aluminum plate based on the analysis of the acoustic waveforms measured by a sensor array located on the thick plate surface in combination with the theoretical Green's function for the plate. The Green's functions are derived based on either the exact elastodynamic or theory the approximate shear deformation plate theory (SDPT). If the displacement is measured on the plate, then the time history of impact load can be calculated by deconvolving the measured displacement with the theoretical Green's function. The reconstructed time history for impact load is compared with the time history of the impact load measured by the force transducer. A good prediction is found. This technique presents a valuable method for identification of source and may be applied to in-service structures under impact to signals recorded from acoustic emission of propagating cracks.

During the service life of reinforced concrete beams (RC beams), they may experience impact loadings induced by various falling objects, such as falling rocks and fragments of upper floors. Therefore, the RC beam’s impact resistance is important to its application in structures. This paper investigated the impact mitigation performance of polyurea coatings on RC beams by drop weight impact tests with different impact velocities and hammer shapes. According to the test results, the polyurea coatings can significantly reduce the RC beams’ local damage and midspan displacement. Moreover, it was found that the RC beams’ plateau impact forces were notably increased by the polyurea coatings. Besides, comparisons between impact tests with different impact loads indicated that the polyurea coatings’ protection effect was not noticeably influenced by the hammer shape or impact velocity. Based on the test results, a numerical model was established and validated, and the model was used to study the mechanism and the parameter influence of polyurea coatings. By simulating the response of upper- and lower-side coated beams, it was revealed that the polyurea coating reduced the RC beam’s overall damage by reducing its local damage and increasing its bending moment. Parametric studies showed that the mitigation effect increased with coating thickness and the increase rate decreased with the thickness. In addition, the effect of longitudinal coating length was also studied via numerical simulation, and it was found that the mitigation effect increased with coating length, and it became nearly identical to that of the fully coated beam when the coating length exceeded 60cm.

Seawall is a most commonly used structure in coastal areas to protect the landscape and coastal facilities. The studies of interactions between the tsunami-like solitary waves and the seawalls are relatively rare in the literature. In this study, a three-dimensional numerical model based on OpenFOAM® was developed to investigate the tsunami-like solitary waves propagating over a rectangular seawall. The Navier–Stokes equations for two-phase incompressible flow, combining with methods of $k-\epsilon$ for turbulence closure and Volume of Fluid (VOF) for tracking the free surface, were solved. Laboratory experiments were performed to measure some of the hydrodynamic feature associated with solitary waves. The model was then validated by the laboratory data, and good agreements were found for free surface, velocity and dynamic pressure around the seawall. Finally, a series of numerical experiments were conducted to analyze the evolution of both wave and flow fields, the overtopping discharge as well as wave pressure (force) around the seawall, special attention is given to the effects of seawall crest width. Our findings will help to improve the understanding in the occurrences of tsunami-induced damages in the vicinity of seawall such as wave impact and local scouring.

Elbow joint loading was evaluated during a forward fall at various elbow initial flexion angles, in order to determine which is the best elbow initial flexion angles to prevent the elbow injury during a fall. Subjects were asked to perform a forward fall and followed by a push-up motion in different elbow initial flexion angles: 0°, 20°, 40° and unrestricted group. Fall on the outstretched hand is the leading cause of upper extremity injury. There are far more extension type of supra-condylar fracture of the elbow than flexion type. Flexion of the elbow may represent the effects of damper and spring. Using the motion analysis system, the kinematics and kinetics of the elbow joint were investigated under various elbow initial flexion angles. The loading biomechanics of the elbow joint differed with various elbow initial flexion angles. The ground reaction forces decrease with increase of elbow flexion upon impact. Different initial elbow flexion angles would affect the biomechanics of upper extremities during falls. Forward fall with elbow in extension is more dangerous. Knowledge of elbow kinematics and kinetics may be helpful in preventing injuries by reducing the ground reaction force with changes of the elbow initial flexion angles during a fall.

The impact on a retaining structure, which is caused by a granular flow comprised of dry particles originated from a shallow landslide failure, still lacks systematic research and is not concerned by the current design code. In order to support the potential requirement of structure design, a series of dry granular impact experiments were done on a rigid retaining wall model as well as on a prefabricated tunnel. For the retaining wall tests a qualitative parametric analysis was done, one nonlinear regression model was proposed to correlate total normal impact force at critical time (F_cr) with its influential parameters. Using statistics one dependency analysis was done. Finally based on the dimension balance principle one non-dimensional equation was proposed, which shows good agreement between prediction and observation results. Some results of the tunnel test were also shown based on the preliminary analysis.

Impact on retaining structures caused by rock fall, granular flow and so on, has drawn researchers' attentions for long time. Some empirical equations for impact force calculation were proposed, but it is rare to find any of them consider the point of action of the impact force. In the companion paper, the authors reported a regression formula which can calculate the impact force of a dry granular flow. In order to complete the whole theory for impact load calculation, this paper addresses the point of action of the critical impact force (h_cr). In the qualitative analysis, the experiment results show the strong fluctuation of h_cr. In the statistical analysis one nonlinear regression model was proposed to correlate h_cr with its influential parameters. After dependency analysis one non-dimensional equation was obtained for h_cr, which shows an acceptable prediction precision.