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Abstract The paper presents a numerical investigation of the ship collision response for a floating pontoon. High fidelity finite element models of a container ship bow and a prestressed concrete pontoon wall are established. The effect of prestressing on the collision resistance of the pontoon is discussed. Integrated numerical simulations are conducted to study the structural deformation and energy absorption of the striking ship and the struck pontoon. The results are compared with the structural responses when a rigid ship collides with a deformable pontoon and a deformable ship collides against a rigid pontoon. Parametric studies are also carried out to investigate the effect of the pontoon wall thickness and the strength and dimension of the ship bulb. A dynamic punching shear check procedure that can be used in the preliminary design phase is proposed. [ABSTRACT FROM AUTHOR]

Bridge piers are designed to withstand not only axial loads of superstructures and passing vehicles but also out-of-plane loads such as earthquake excitations and vessel impact loads. Vessel impact on bridge piers can lead to substantial damages or even collapse of bridge structures. An increasing number of vessel collision accidents have been reported in the past decade. A lot of researches have been conducted for predicting barge impact loads and calculating structural responses. However, in practice it is not possible to design bridge structures to resist all levels of barge impact loads. Moreover, with an increasing traffic volume and vessel payload in some waterways, the bridge piers designed according to previous specifications might not be sufficient to resist the current vessel impact loads. Therefore, strengthening existing bridge piers are sometimes necessary for protecting structures from barge impact. Carbon fiber reinforced polymer (CFRP) has been widely used in strengthening reinforced concrete structures under impulsive loadings. It is an effective material which has been proven to be able to increase the flexural strength of structures. In this study, CFRP composites are used to strengthen reinforced concrete piers against barge impact loads. Pendulum impact tests are conducted on scaled pier models. Impact force and pier response with and without CFRP strengthening are compared. The effectiveness of using CFRP strengthening the pier model is observed. In addition, numerical models of the bridge piers are developed and calibrated with experimental results. Parametric simulations of barge impacting on piers with or without CFRP strengthening are carried out. The results show that compared with unstrengthened pier, CFRP composite strengthened bridge pier has a higher impact resistance capacity and hence endures less structural damage under the same barge impact load. The effectiveness of CFRP strengthening with different CFRP thickness, CFRP strength and bond strength between the pier and the CFRP composite are also discussed. [ABSTRACT FROM AUTHOR]

Abstract: Bridge structures across navigable waterways are vulnerable to barge collisions. To protect the bridge structure, bridge piers should be specially designed to resist barge impact load. In order to quantify the impact load, barge–pier impact tests and/or reliable theoretical or numerical predictions should be conducted. However, very limited impact tests were carried out to evaluate barge impact force and pier response due to the cost and site limitations. This paper presents laboratory tests and numerical simulation results of barge impacting on bridge piers. A scaled circular reinforced concrete pier is built and tested first with a pendulum impact test system. Impact load profile and pier top displacement were recorded and analyzed. A numerical model is then developed to simulate the laboratory tests. Nonlinear materials are used to model the concrete and steel reinforcements with strain rate effects. The accuracy of the pier model is calibrated by comparing the experimental and numerical results. Using the validated numerical model, a full scale bridge pier model is developed to simulate the barge impact on bridge piers. Pile groups and soil springs are considered to model the soil–pier interaction. Parametric studies are carried out to investigate the effects of barge impact velocity, barge mass, pier diameter and height, superstructure mass and impact location, and soil–pier interaction. Impact load time history and pier displacement response are calculated. Based on the numerical results, empirical formulae are proposed to predict the peak impact force and impulse. The adequacy of the current design code is also discussed in the paper. [Copyright &y& Elsevier]

Abstract: Vessel collisions with bridge piers are one of the most frequent accidents that may lead to bridge failure. To reliably assess bridge response and damage due to barge impact, and design the bridge piers to resist such impact, the impact force should be accurately defined. In most of the previous works of numerical simulation of barge collision with bridge piers for defining the barge impact force, the pier was assumed to be rigid or elastic and the interaction between the barge and the pier was neglected. As pier plastic deformation and damage will absorb impact energy and also prolong the interaction time, the impact force acting on the bridge pier might not be accurately predicted with rigid and elastic pier assumption. In this paper, a detailed numerical model of barge–pier impact is developed in LS-DYNA. The bridge pier is modelled with nonlinear materials to more realistically generate the bridge pier characteristics. Barge–pier impact force time history, barge crush depth and pier displacements are calculated in this paper. The reliability of the numerical model is calibrated with some results available in the literature. Based on numerical results simplified formulae are derived to predict the impact force time history with respect to the collision conditions. Numerical results are compared with the previous works. The adequacy of current code specifications is also discussed. [Copyright &y& Elsevier]

• The plane blast wave with a long action time is engendered by an explosion container. • The laser welding technology for millimeter-meter-level steel corrugated sandwich panels. • The deformation mechanism of the two laser-welded sandwich panels is investigated to study the anti-blast performance. • A simplified theoretical method is used to calculate the deformation of the sandwich panel under the plane blast wave based on the numerical simulation technology. A plane blast wave with long-time effect was achieved inside an explosion container by experiment, and was applied to laser-welded corrugated sandwich panels to study the dynamic response characteristics. The deformation model of the panels was investigated, including the cores and faceplates. The results indicate that the deformation between the top and bottom face is not consistent in different directions, and the impact accelerations and deformation are not similar in relative variation with core height. Numerical simulations were applied to reproduce the experimental phenomenon. The consensus was reached that the simulation results were convincing. Based on the numerical simulation technique, a simplified analysis method using equivalence theory and three stages analysis under the plane blast wave was proposed. After comparing the calculated results, the applicable scope of the simplified method in the core height and pressure peak was also determined. [ABSTRACT FROM AUTHOR]

Abstract This paper reports the further study carried out by the authors on the technique of long-hole raising in one blast. In the previous work reporting the results of preliminary study, method of vertical crater retreat (VCR) multiple-deck shots with different and smaller slice heights was used to excavate the raise in one blast. A 32-m raise in the cover of an abandoned cavity was successfully broken through. In this paper, an improved technique is suggested to overcome the overbreak and freezing in a long-hole raising blast. In the raising process, long-hole presplitting is first performed at the periphery of the blasting pattern, and then inner VCR multiple-deck shots with the same slice height are conducted according to a specific initiation sequence without in-slice delays. The previously calibrated numerical model is used to simulate the blasting process. The rock mass behaviours and the raising mechanisms are examined. It is shown that after the introduction of long-hole presplitting, the overbreak and freezing are greatly relieved, and the direction of advance and timing pattern are vitally responsible for the evolution of rock damage. This suggested technique was then applied to field raising blasts, and a 29-m raise and a 24-m raise under special cavity conditions were successfully developed. It demonstrates that, compared to the method of purely VCR multiple-deck shots, the design process can be greatly simplified and the present technique leads to better blasting performances. [ABSTRACT FROM AUTHOR]