共查询到16条相似文献,搜索用时 156 毫秒
1.
基于碰撞分析的特高防撞等级桥梁护栏安全评价 总被引:6,自引:2,他引:4
为降低危险路段车辆穿越护栏造成恶性事故的概率,提出特高防撞等级桥梁护栏设计方案,采用有限元仿真和实车足尺碰撞试验相结合的技术手段,对其安全性能进行评价。结果表明,车辆碰撞护栏后能够平稳驶出,并能够恢复到正常行驶姿态,小型车驶出角度为6.6°,大型车驶出角度为4.6°,大货车碰撞护栏动态位移最大值为347mm,小车重心处加速度最大值为16.7g;仿真结果与试验结果相一致,误差在10%以内。可见护栏各项指标均满足评价标准要求,具备630kJ防撞能力,可以在实际工程中应用,同时也表明运用仿真方法进行护栏安全评价具有一定的可行性。 相似文献
2.
为消除伸缩缝处的安全隐患,建立经碰撞试验验证的有限元仿真模型,对大跨径伸缩缝处事故形态进行分析,提出伸缩缝处的护栏结构并进行安全评价.对于这种组合式护栏的计算和试验,结果表明:仿真计算与碰撞试验结果一致,误差在15%以内,可作为分析评价伸缩缝处护栏安全防护性能的方法;时速100km/h、重1.5t的小客车和时速为65km/h、重22t的大货车碰撞伸缩缝护栏后,能够平稳驶出且恢复到正常行驶姿态,驶出角度分别为9°和0°;小客车车体X、Y、Z三方向加速度最大值分别为13g、17.8g和10.2g;护栏最大动态位移为200mm.伸缩缝护栏各项指标均满足评价标准要求,可有效消除伸缩缝处的安全隐患. 相似文献
3.
4.
针对城市快速路对桥侧护栏的安全性、绿化、协调性的特殊需求,参考国内外相关标准提出城市快速路桥侧护栏碰撞条件和评价标准,开发出具有综合功能的桥侧护栏,并利用有限元仿真技术手段进行安全评价。研究结果表明,桥侧混凝土护栏结构能够有效防护车辆,小客车碰撞后驶出角度为7°,大客车碰撞后驶出角度为1.7°,小客车碰撞后重心加速度最大值为17.4g,大客车碰撞后护栏最大动态变形小于100mm,护栏达到SS级520kJ的防撞能力。护栏可进行绿化物种植,并能和灯杆、标志牌等协调安装。此种桥侧护栏已在实际工程中应用。 相似文献
5.
提出一种自防眩高防撞等级中央分隔带桥梁护栏结构,并运用计算机仿真方法对其进行安全性能分析。结果表明自防眩高防撞等级中央分隔带桥梁护栏能够有效防护车辆,小客车碰撞后驶出角度为3.5°,大客车碰撞后驶出角度为4.3°,大货车碰撞后驶出角度为6.3°;小客车碰撞后重心加速度最大值为18.5g;大客车和大货车碰撞后护栏最大动态变形量均小于50mm,且大货车碰撞后护栏最大动态变形量为大客车碰撞后的1.48倍,说明相同碰撞能量下,大货车对护栏的破坏程度大于大客车。自防眩高防撞等级中央分隔带桥梁护栏各项指标均满足评价标准要求,防撞等级达到SAm级,并在依托工程中实施应用。 相似文献
6.
7.
为了解整体货车和拖头货车碰撞护栏的不同特性,建立经碰撞试验验证的有限元仿真模型,对两种车型碰撞护栏进行分析。结果表明,时速为65km/h、重33t的整体车和拖头车以20°角碰撞护栏后,能够平稳驶出且恢复到正常行驶姿态;整体车碰撞护栏碰撞力峰值出现2次,拖头车碰撞护栏碰撞力峰值出现3次,整体车最大碰撞力大于拖头车最大碰撞力;整体车驶出角度为4.2°,拖头车驶出角度为2°;整体车碰撞护栏动态位移最大为315mm,拖头车碰撞护栏最大动态位移为158mm。可见相同碰撞条件下,拖头车对护栏的破坏小于整体车。 相似文献
8.
9.
10.
对防撞护栏的设计方法和设计条件进行了系统性的论述。采用ANSYS/LS-DYNA3D软件,通过计算机仿真对车辆与梁柱式防撞护栏的碰撞过程进行分析,提出了改正这种梁柱式防撞护栏的措施,并对改正后的防撞护栏进行了碰撞分析,表明改正后的防撞护栏可以有效地将碰撞车辆导向车道。 相似文献
11.
12.
《Energy and Buildings》2004,36(5):415-422
The potential of controlling techniques for an electrochromic device is investigated in a systematic way, using both experimental and theoretical tools. Concerning the theoretical part a model was developed in the TRNSYS environment and validated against experimental data. These data were collected from experiments, which were carried out in a PASSYS test cell with a movable wall. Having established a good model performance several cases of window types (such as a 4 mm clear window and a low-e double glazing) and controlling strategies for the electrochromic device are simulated. Obtained results from the series of simulations were compared in terms of the heating and cooling loads of the test cell for each case. It was found that the development of a scheduled control strategy for the electrochromic glazing is better in terms of cooling loads. Finally, a more sophisticated control strategy was examined based on the adaptive fuzzy approach. 相似文献
13.
An open-air experimental apparatus was built to define a common procedure for the thermal properties evaluation of low-e barriers, whose performance in static and dynamic conditions is still an object of debate. The structure hosts a movable wall where single layers can be substituted, allowing the defining of the properties of the system radiant barrier-air gaps, independently of the rest of stratigraphy. The steady-state results have been compared with other methods commonly used for low-e materials such as the guarded hot plate, the hot box method, and the theoretical analysis based on hemispherical emissivity measurements, showing a good agreement among the different approaches. The transient analysis demonstrated that the proposed experimental apparatus permits the direct definition of the radiant barrier dynamic properties, through a previous characterization of the structure without the low-e panel. In fact, when the panel is installed, the performance of the sole package panel-air gaps is easily obtained reducing the errors due to the interference of the rest of the stratigraphy. 相似文献
14.
The Thames barrier became operational in October 1982. Much work had been done and many problems solved since the Greater London Council was asked to investigate the construction of a movable barrier across the Thames, in 1968. The project management of the scheme is described, with some of the problems experienced along the way. 相似文献
15.
针对普通混凝土道面易开裂、使用寿命无法达到设计寿命的情况,在普通混凝土中加入合成聚丙烯纤维及聚丙烯腈纤维,以提高混凝土的抗弯拉开裂性能及冲击韧性。对改性合成聚丙烯纤维混凝土及聚丙烯腈纤维混凝土进行了四点弯曲试验,并采用自行设计的冲击试验装置进行了冲击试验及经冻融循环后冲击试验。试验结果表明:在几乎不影响抗压强度的情况下,长度20、40 mm的合成聚丙烯纤维可以显著提升混凝土的抗弯韧性和冲击次数,经冻融后合成聚丙烯纤维混凝土的冲击次数下降幅度明显低于普通混凝土; 在抗弯韧性及抗冲击性能方面,改性合成聚丙烯纤维改善效果最佳,聚丙烯腈纤维次之,而长度40 mm的合成聚丙烯纤维又略强于长度20 mm的合成聚丙烯纤维; 在抗弯韧性方面,掺有长度40 mm合成聚丙烯纤维混凝土相较素混凝土提升了60.09%~120.62%; 未经冻融前掺有长度40 mm合成聚丙烯纤维混凝土在冲击试验中的初裂冲击次数和破坏冲击次数均为最高,相较素混凝土分别提升了114.29%~157.14%和120%~306.67%,相较于掺有长度为20 mm合成聚丙烯纤维的混凝土分别提升了5.56%~23.53%和15.15%~35.90%,相较于掺有聚丙烯腈纤维的混凝土分别提升了5.56%~13.33%和36.36%~60.66%; 试验结果可为混凝土道面的建设提供参考依据。 相似文献
16.
《Journal of Building Performance Simulation》2013,6(3):191-204
Moisture-induced damage is one of the major causes of degradations and reduced thermal performance in wood frame buildings. It is therefore crucial to incorporate the hygrothermal assessment of new timber frame building envelopes systems from the early development phase onwards. The article at hand presents the simulation results studying the hygrothermal performance of various timber frame wall configurations with exterior air barrier systems. A parameter analysis explores the impact of different European climates, insulation materials, exterior air barrier materials and verifies in addition to the impact of bad workmanship in the installation of the insulation layer. This study reveals that the application of mineral wool (MW) insulated timber frame walls in combination with exterior air barriers results in increased moisture loads. Moreover, small air gap channels between the MW and the adjacent exterior air barrier significantly increase natural convection and add up to harmful moisture levels. Yet the simulations indicate that the use of blown-in cellulose insulation can avoid these issues. The study further indicates that the technique of exterior air barrier is more suitable for continental climates rather than for moderate sea climates in Europe. 相似文献