Fire is a quite common phenomenon in tunnel and being able to model its consequences with a good precision is crucial to design adapted safety measures.Modelling the fire behaviour in tunnel is quite challenging.Manag...Fire is a quite common phenomenon in tunnel and being able to model its consequences with a good precision is crucial to design adapted safety measures.Modelling the fire behaviour in tunnel is quite challenging.Managing large-scale experiment for all the possible configurations is however economically unrealistic.This paper presents an experimental real scale fire test that was used not only for demonstrating the fire behaviour but also for evaluating the capabilities of the FDS(fire dynamics simulator)fire code to model fire consequences too.It enables highlighting the importance of wall and inlet boundary condition treatment.Keeping in mind that predicting fire development using a CFD(computational fluid dynamics)code is quite impossible,a two-level approach is discussed with an analytical model to predict the fire curve and a CFD model for predicting smoke propagation,temperature and toxic gases distribution inside the tunnel.The comparisons show a good agreement between experimental fire test and CFD modelling but also let appear requirements when using CFD.展开更多
In order to investigate the behavior of external welded flange-bolted web joints of steel structure exposed to fire,a series of experiments were carried out.Influence of fire model and load ratio on the behavior of th...In order to investigate the behavior of external welded flange-bolted web joints of steel structure exposed to fire,a series of experiments were carried out.Influence of fire model and load ratio on the behavior of the joints,failure characteristics and fracture modes of the joints exposed to fire were studied.The experimental results indicated that the fire model has a great influence on the temperature rising as well as temperature distribution of the joints exposed to fire.A slower temperature rising fire will lead to slower temperature rising and more uniform temperature distribution of joint.Decrease of the load ratio will improve the fire-resistant capability of the joint.Furthermore,a highly detailed three-dimensional(3-D) finite element model(FEM) was set up with ANSYS software to predict the behavior of the external welded flange-bolted web joints exposed to fire.Comparisons between the predicted results and the experimental results indicated that FEM has an acceptable degree of accuracy to predict the behavior of this type of joints exposed to fire.展开更多
针对实弹射击训练场地条件限制大、训练耗费较高、安全保障困难以及训练内容无法适时弹性变更的问题,提出了仿真系统基于射表的外弹道仿真方法,以射表数据为输入、系统设定外界环境为修正的抛物线拟合弹丸质心方程组,通过方程组拟合获...针对实弹射击训练场地条件限制大、训练耗费较高、安全保障困难以及训练内容无法适时弹性变更的问题,提出了仿真系统基于射表的外弹道仿真方法,以射表数据为输入、系统设定外界环境为修正的抛物线拟合弹丸质心方程组,通过方程组拟合获得较为切合实际外弹道的曲线模型;以C++作为开发语言对外弹道进行拟合运算,实时显示弹丸运动轨迹,由此获得室内训练场环境的模拟模型,并将误差控制在一定范围内;使用Unity3D为虚拟引擎,将驱动坦克与炮弹引入三维可视化实体模型,并搭建相应地形场景与命中效果;应用3D Studio Max软件建立坦克与炮弹实体模型,体现战场环境多变性与射击系统过程的仿真模拟,为外弹道及射击仿真训练系统提供了研究基础。展开更多
文摘Fire is a quite common phenomenon in tunnel and being able to model its consequences with a good precision is crucial to design adapted safety measures.Modelling the fire behaviour in tunnel is quite challenging.Managing large-scale experiment for all the possible configurations is however economically unrealistic.This paper presents an experimental real scale fire test that was used not only for demonstrating the fire behaviour but also for evaluating the capabilities of the FDS(fire dynamics simulator)fire code to model fire consequences too.It enables highlighting the importance of wall and inlet boundary condition treatment.Keeping in mind that predicting fire development using a CFD(computational fluid dynamics)code is quite impossible,a two-level approach is discussed with an analytical model to predict the fire curve and a CFD model for predicting smoke propagation,temperature and toxic gases distribution inside the tunnel.The comparisons show a good agreement between experimental fire test and CFD modelling but also let appear requirements when using CFD.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50676089)
文摘In order to investigate the behavior of external welded flange-bolted web joints of steel structure exposed to fire,a series of experiments were carried out.Influence of fire model and load ratio on the behavior of the joints,failure characteristics and fracture modes of the joints exposed to fire were studied.The experimental results indicated that the fire model has a great influence on the temperature rising as well as temperature distribution of the joints exposed to fire.A slower temperature rising fire will lead to slower temperature rising and more uniform temperature distribution of joint.Decrease of the load ratio will improve the fire-resistant capability of the joint.Furthermore,a highly detailed three-dimensional(3-D) finite element model(FEM) was set up with ANSYS software to predict the behavior of the external welded flange-bolted web joints exposed to fire.Comparisons between the predicted results and the experimental results indicated that FEM has an acceptable degree of accuracy to predict the behavior of this type of joints exposed to fire.
文摘针对实弹射击训练场地条件限制大、训练耗费较高、安全保障困难以及训练内容无法适时弹性变更的问题,提出了仿真系统基于射表的外弹道仿真方法,以射表数据为输入、系统设定外界环境为修正的抛物线拟合弹丸质心方程组,通过方程组拟合获得较为切合实际外弹道的曲线模型;以C++作为开发语言对外弹道进行拟合运算,实时显示弹丸运动轨迹,由此获得室内训练场环境的模拟模型,并将误差控制在一定范围内;使用Unity3D为虚拟引擎,将驱动坦克与炮弹引入三维可视化实体模型,并搭建相应地形场景与命中效果;应用3D Studio Max软件建立坦克与炮弹实体模型,体现战场环境多变性与射击系统过程的仿真模拟,为外弹道及射击仿真训练系统提供了研究基础。
