Analysis of girder bridge pier subjected to barge collision considering the superstructure interactions: the case study of a multiple-pier bridge system

This paper aims to numerically evaluate the effects of girder bridge superstructure on the impact responses and load paths transferring the shear force of pier subjected to a moderate-energy barge collision in LS-DYNA. First, two multiple-pier systems of St. George Island Bridge in Florida which have different piers in terms of structural characteristics (such as mass and stiffness), geometry, and the height of impact location are considered as the cases of study. From the numerical barge collision simulations, different impact responses and load transferring paths from the impact location to farther zones are observed. In addition, the sensitivity of impact responses, and the impact load paths transferring shear force to the superstructure mass, stiffness, and damping are studied by developing four different models of pier-superstructure interaction and carrying out a parametric study. It is found that the increase in the value of superstructure parameters has positive effects on the impact forces and the internal stresses in the piers. However, the sensitivity of shear stresses generated at various zones of the pier extremely depends on the impact load paths transferring shear force in different piers with different relative characteristics rather than the superstructure.     

一种新型浮式综合发电平台的概念设计及其动态响应研究

参照OC3-Hywind Spar Buoy和1TI Energy Barge(以下分别简称Spar和Barge)的结构特点,提出了一种新型浮式综合发电平台的概念,根据海洋能发电的特性,构建了“风能-太阳能-波浪能”的联合发电系统,以实现多种能源的耦合互补,并以我国南海作为平台工作条件,采用ANSYS的水动力学模块对平台进行了数值计算.结果表明:该平台的动态响应较小,水动力性能良好,适合在南海海域使用.     

系泊参数对漂浮式风力机平台的影响研究

海上漂浮式风力机的研究已成为风电领域的重点与热点,而系泊对漂浮式风力机平台的安全有极其重要的影响,因此本文选取基于Barge平台的NREL 5MW漂浮式风力机作为研究对象,研究系泊参数对漂浮式风力机动态响应及系泊缆张力的影响。结果表明:系泊直径和系泊长度的变化对漂浮式风力机纵摇及系泊缆顶端张力影响较大,对垂荡和纵摇影响较小;当系泊直径为0.3m时,纵荡位移偏移量达到最大,系泊缆顶端张力达到最小;随着系泊长度的增长,纵荡位移不断增大,系泊缆顶端张力不断减小。     

Routing of barge container ships by mixed-integer programming heuristics

We investigate the optimization of transport routes of barge container ships with the objective to maximize the profit of a shipping company. This problem consists of determining the upstream and downstream calling sequence and the number of loaded and empty containers transported between any two ports. We present a mixed integer linear programming (MILP) formulation for this problem. The problem is tackled by the commercial CPLEX MIP solver and improved variants of the existing MIP heuristics: Local Branching, Variable Neighborhood Branching and Variable Neighborhood Decomposition Search. It appears that our implementation of Variable Neighborhood Branching outperforms CPLEX MIP solver both regarding the solution quality and the computational time. All other studied heuristics provide results competitive with CPLEX MIP solver within a significantly shorter amount of time. Moreover, we present a detailed case study transportation analysis which illustrates how the proposed approach can be used by managers of barge shipping companies to make appropriate decisions and solve real life problems.     

基于MTMD的Barge型漂浮式风力机稳定性控制研究

为提高漂浮式风力机的稳定性,以NREL 5 MW风力机及ITI Barge平台为控制对象,在传统单个调谐质量阻尼器(STMD)基础上提出风力机机舱及塔架中配置不同动力特性调谐质量阻尼器(TMD)的新型多重调谐质量阻尼器(MTMD)控制方法,分别研究其在环境载荷作用下队海上漂浮式风力机稳定性的控制效果。研究表明:STMD及MTMD对漂浮式风力机塔顶左右位移控制效果较明显,波动范围分别减小38%和45%,稳定性分别提高41%和46%;在STMD及MTMD控制下,漂浮式风力机平台横荡和横摇降幅明显;MTMD对漂浮式风力机塔架和平台的动态响应控制效果优于STMD控制。     

Efficacy of increasing discharge to reduce tow-mediated fish passage across an electric dispersal barrier system in a confined channel

The Electric Dispersal Barrier System (EDBS) in the Chicago Sanitary and Ship Canal (CSSC) was built to limit the interbasin transfer of aquatic invasive species between the Mississippi River Basin and the Great Lakes Basin. Commercial barge traffic, or tows, moving downstream through the EDBS can facilitate the upstream passage of small fish through the barrier by reducing the voltage gradient of the barrier and causing localized upstream return currents. This study tested whether it is possible to prevent upstream passage of small fish across the barrier by preventing upstream return currents. Measurements of water velocity, voltage gradient, and tow speed, as well as sonar-based observations of resident fish, were made as a tow transited the EDBS moving downstream. The results indicate that upstream return currents can be prevented for typical flow conditions in the CSSC (ambient velocity = 0.15 to 0.23 m/s) when tow speeds are <0.46 m/s. Similarly, increasing the ambient velocity above typical values can prevent upstream return currents for faster tow speeds and larger tows. Additionally, preventing upstream return currents at the EDBS may reduce, but does not prevent, tow-mediated upstream fish passages because tows also cause a temporary reduction in the streamwise voltage gradient at the EDBS. These results have implications for the management of invasive bigheaded carps in the Illinois Waterway.     

三峡工程升船机高边坡预锚施工与监测成果分析

三峡工程升船机基础高边坡采用了大量的预应力锚索进行加固,由于早强材料的使用和合理的施工组织,较好地解决了岩锚工程施工工序的突出交叉矛盾和施工工期问题.通过对长达一年的监测成果分析,表明预锚达到了预期效果.     

叠彩山出口升船机承船厢结构布置及参数选择

针对升船机为船厢下水运行的特点，论述承船厢的结构布置和主要技术参数选择。     

Effects of soil–pile interaction on the response of bridge pier to barge collision using energy distribution method

Abstract

In this paper, the effects of soil–structure interaction (SSI) on the response of a girder bridge pier is evaluated by assessing the energy distributions in the barge–pier collision system. The finite-element models of two example piers of St. George Island Causeway Bridge, which have different structural and geometrical characteristics, are developed in LS-DYNA software to simulate the barge–pier collision scenarios. By comparing the energy distribution results among the barge and pier components, it is obtained that barge bow component has greater value of the internal energy contribution than pier components in the barge collision with more stiff pier. While, in the barge collision with more flexible pier, the pier components including the pier structure, piles and SSI have more internal energy contributions than the barge component. In addition, From the comparison of energy absorbed by the pier structure between the cases with and without SSI, it is found that the effect of the substructure and its relevant SSI on the response of the more flexible pier affected by the produced large deformations and relative displacements of the pier substructure, is more than that of stiff pier which displaces with semi-rigid and global deflections.