水线面大开口型工程船的阻力试验和节能措施

文章通过船模试验研究了水线面大开口型工程船的静水阻力和波浪阻力特性。结果显示,水线面大开口型工程船的艏艉开槽大大增加了船体的静水阻力,但对船体波浪增阻的影响却并不明显。同时,用模型试验和实船试验共同验证了此类船舶航行时双舵内偏一个角度能明显提高航速,是一项有效的节能措施。     

广东省柔性基层沥青路面设计弯沉计算参数研究

通过分析现行沥青路面设计规范中设计弯沉计算公式的由来及在广东省的适用情况,结合广东省最早修建的几条高速公路沥青路面的路况资料,对柔性基层沥青路面设计弯沉相关计算参数进行了研究,标定了沥青路面设计弯沉计算公式。此外,通过力学分析计算广东省内常见的半刚性、组合式及柔性路面结构中柔性层的总厚度及层底弯拉应力的受力状况,提出了弯沉计算参数不同取值的适用条件。     

Research on the dynamic buckling of a typical deck grillage structure subjected to in-plane impact Load

The dynamic buckling of the main deck grillage would result in the total collapse of the ship hull subjected to a far-filed underwater explosion. This dynamic buckling is mainly due to the dynamic moment of the ship hull when the ship hull experiences a sudden movement under impact load from the explosion. In order to investigate the ultimate strength of a typical deck grillage under quasi-static and dynamic in-plane compressive load, a structure model, in which the real constrained condition of the deck grillage was taken into consideration, was designed and manufactured. The quasi-static ultimate strength and damage mode of the deck grillage under in-plane compressive load was experimentally investigated. The Finite Element Method (FEM) was employed to predict the ultimate strength of the deck grillage subjected to quasi-static in-plane compressive load, and was validated by comparing the results from experimental tests and numerical simulations. In addition, the numerical simulations of dynamic buckling of the same model under in-plane impact load was performed, in which the influences of the load amplitude and the frequency of dynamic impact load, as well as the initial stress and deflection induced by wave load on the ultimate strength and failure mode were investigated. The results show that the dynamic buckling mode is quite different from the failure mode of the structure subjected to quasi-static in-plane compressive load. The displacements of deck edge in the vertical direction and the axial displacements are getting larger with the decrease of impact frequency. Besides, it is found that the dynamic buckling strength roughly linearly decreased with the increase of initial proportion of the static ultimate strength P₀. The conclusions drawn from the researches of this paper would help better designing of the ship structure under impact loads.     

基于同板弯沉差的板底脱空判定方法

针对同一路面板的板中、板边、板角之间弯沉差与板底脱空的关系在规范中并未有明确说明,且国内外研究也较少的情况,以烟台～威海高速路试验段为依托工程,对板底脱空的弯沉评价指标进行了理论计算。采用贝克曼梁弯沉仪(BB)和落锤式弯沉仪(FWD)对比测量,并计算同板板中与板边中点、板角弯沉差,在此基础上,经统计分析方法确定了静动弯沉值判定脱空的评定标准。试验路的钻芯结果表明,基于同板弯沉差的板底脱空判定方法具有较高的可信度。     

梁桥恒载跨中挠度允许值[ft]确定

长期以来,我国桥规对梁桥恒载跨中挠度允许值[ft]空缺;一般均用活载挠度fp=[L/600]来代替。这是造成中国PC连续梁跨中普遍下挠、底板开裂的一个重要原因。文中提出设计应控制合龙前初始挠度[f0]≤L/4 800才能确保桥梁安全。     

大跨径连续PC梁桥悬臂施工挠度的影响因素分析及控制措施

针对目前悬臂施工线性控制中容易出现高程波动,超出规范要求的实际施工情况,从影响桥梁悬臂施工的各参数出发,进行了定性分析,得出了桥梁悬臂施工挠度显著的敏感性因素,并提出了施工中采取的措施。     

高速公路标志牌偏转角优化设计研究

针对长湘高速双向六车道标志牌的遮挡问题,根据光的逆反射性能及驾驶员对标志的视认性,通过计算不同偏转角度下入射角的大小对反射角的影响关系,得出了标志牌的最佳偏转角度。     

车辆荷载作用下脱空地基上CRCP板的挠度研究

基于连续配筋混凝土路面板挠度等效原则,转换了板中车辆集中荷载时的荷载作用模式。运用弹性薄板理论,推导出车辆集中荷载作用于板中时脱空的连续配筋混凝土路面板的挠度计算公式,同时运用有限元挠度计算结果对理论公式挠度计算结果进行了对比验证,两者基本吻合。     

Enhancing grey prediction fuzzy controller for active suspension systems

A grey prediction fuzzy controller (GPFC) was proposed to control an active suspension system and evaluate its control performance. The GPFC employed the grey prediction algorithm to predict the position output error of the sprung mass and the error change as input variables of the traditional fuzzy controller (TFC) in controlling the suspension system to suppress the vibration and the acceleration amplitudes of the sprung mass for improving the ride comfort of the TFC used; however, the TFC or GPFC was employed to control the suspension system, resulting in a large tire deflection so that the road-holding ability in the vehicle becomes worse than with the original passive control strategy. To overcome the problem, this work developed an enhancing grey prediction fuzzy controller (EGPFC) that not only had the original GPFC property but also introduced the tire dynamic effect into the controller design, also using the grey prediction algorithm to predict the next tire deflection error and the error change as input variables of another TFC, to control the suspension system for enhancing the road-holding capability of the vehicle. The EGPFC has better control performances in suppressing the vibration and the acceleration amplitudes of the sprung mass to improve the ride quality and in reducing the tire deflection to enhance the road-holding ability of the vehicle, than both TFC and GPFC, as confirmed by experimental results.     

强夯法处理石灰岩碎石路基试验研究

结合常吉高速公路路基强夯的工程实践,对石灰岩碎石路基进行了强夯试验研究,分析了强夯法处理石灰岩碎石路基的效果,提出了该段路基强夯设计参数。现场进行了夯沉量、压实度和弯沉测试,以及碎石土级配分析和素土含量试验。根据理论分析和试验结果,路基在1 200 kN.m夯击能作用下夯击3锤,夯沉量可达到30 cm以上,压实度可提高5%,达95%以上,达到规范和建成后的安全使用要求;路基填料的级配及素土含量情况直接影响路基的夯沉量,碎石级配越好,素土含量适当,路基的夯沉量就越小。