Double-layer model updating for steel-concrete composite beam cable-stayed bridge based on GPS

In order to establish the relationship between the measured dynamic response and the health status of long-span bridges, a double-layer model updating method for steel-concrete composite beam cable-stayed bridges is proposed. Measured frequencies are selected as the first-layer reference data, and the mass of the bridge deck, the grid density, the modulus of concrete and the ballast on the side span are modified by using a manual tuning technique. Measured global positioning system （GPS） data is selected as the second-layer reference data, and the degradation of the integral structure stiffness EI of the whole bridge is taken into account for the second-layer model updating by using the finite element iteration algorithm. The Nanpu Bridge in Shanghai is taken as a case to verify the applicability of the proposed model updating method. After the first-layer model updating, the standard deviation of modal frequencies is smaller than 7%. After the second-layer model updating, the error of the deflection of the mid-span is smaller than 10%. The integral structure stiffness of the whole bridge decreases about 20%. The research results show a good agreement between the calculated response and the measured response.

High-stability double-layer polymer-inorganic composite electrolyte fabricated through ultraviolet curing process for solid-state lithium metal batteries

Electrolyte interface resistance and low ionic conductivity are essential issues for commercializing solid-state lithium metal batteries(SSLMBs).This work details the fabrication of a double-layer solid composite electrolyte(DLSCE)for SSLMBs.The composite comprises poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP)and poly(methyl methacrylate)(PMMA)combined with 10 wt.%of Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO),synthesized through an ultraviolet curing process.The ionic conductivity of the DLSCE(2.6×10^(-4) S·cm^(-1))at room temperature is the high lithium-ion transference number(0.57),and the tensile strength is 17.8 MPa.When this DLSCE was assembled,the resulted LFP/DLSCE/Li battery exhibited excellent rate performance,with the discharge specific capacities of 162.4,146.9,93.6,and 64.0 mA·h·g^(-1) at 0.1,0.2,0.5,and 1 C,respectively.Furthermore,the DLScE demonstrates remarkable stability with lithium metal batteries,facilitating the stable operation of a Li/Li symmetric battery for over 200 h at both 0.1 and 0.2 mA-cm^(-2).Notably,the formation of lithium dendrites is also effectively inhibited during cycling.This work provides a novel design strategy and preparation method for solid composite electrolytes.

Consolidation analysis of composite foundation with partially penetrated cement fly-ash gravel(CFG) piles under changing permeable boundary conditions

Based on the double-layered foundation theory, the composite ground with partially penetrated cement fly-ash gravel(CFG) piles was regarded as a double-layered foundation including the surface reinforced area and the underlying untreated stratum. Due to the changing permeability property of CFG piles, the whole consolidation process of the composite ground with CFG piles was divided into two stages, i.e., the early stage(permeable CFG pile bodies) and the later stage(impermeable pile bodies). Then, the consolidation equation of the composite foundation with CFG piles was established by using the Terzaghi one-dimensional consolidation theory. Consequently, the unified formula to calculate the excess pore water pressure was derived with the specific solutions for the consolidation degree of composite ground, reinforced area and underlying stratum under instant load obtained respectively. Finally, combined with a numerical example, influencing rules by main factors(including the replacement rate m, the treatment depth h1, the permeability coefficient Ks1, Kv2 and compression modulus Es1, Es2 of reinforced area and underlying stratum) on the consolidation property of composite ground with CFG piles were discussed in detail. The result shows that the consolidation velocity of underlying stratum is slower than that of the reinforced area. However, the consolidation velocity of underlying stratum is slow at first then fast as a result of the transferring of effective stress to the underlying stratum during the dissipating process of excess pore water pressure.

In-situ constructed polymer/alloy composite with high ionic conductivity as an artificial solid electrolyte interphase to stabilize lithium metal anode

Lithium(Li)metal is regarded as the best anode material for lithium metal batteries(LMBs)due to its high theoretical specific capacity and low redox potential.However,the notorious dendrites growth and extreme instability of the solid electrolyte interphase(SEI)layers have severely retarded the commercialization process of LMBs.Herein,a double-layered polymer/alloy composite artificial SEI composed of a robust poly(1,3-dioxolane)(PDOL)protective layer,Sn and LiCl nanoparticles,denoted as PDOL@Sn-LiCl,is fabricated by the combination of in-situ substitution and polymerization processes on the surface of Li metal anode.The lithiophilic Sn-LiCl multiphase can supply plenty of Li-ion transport channels,contributing to the homogeneous nucleation and dense accumulation of Li metal.The mechanically tough PDOL layer can maintain the stability and compact structure of the inorganic layer in the long-term cycling,and suppress the volume fluctuation and dendrites formation of the Li metal anode.As a result,the symmetrical cell under the double-layered artificial SEI protection shows excellent cycling stability of 300 h at 5.0 mA·cm^(−2)for 1 mAh·cm^(−2).Notably,the Li||LiFePO_(4)full cell also exhibits enhanced capacity retention of 150.1 mAh·g^(−1)after 600 cycles at 1.0 C.Additionally,the protected Li foil can effectively resist the air and water corrosion,signifying the safe operation of Li metal in practical applications.This present finding proposed a different tactic to achieve safe and dendrite-free Li metal anodes with excellent cycling stability.

北京某地下人行通道的加固处理

对北京某地下人行通道出现的挠度大、残余变形大等问题进行了分析。原结构较大面积的严重渗水致使混凝土的耐久性能受损、钢筋严重锈蚀是问题产生的主要原因。针对这些原因 ,通过方案比较和优化 ,提出了经济实用的钢 混凝土组合结构加固方案 。

人防工程平时出入口临战快速封堵方法

为了解决已建人防工程实施临战快速封堵问题,采用新型轻骨料混凝土复合梁构筑隔墙进行抗爆封堵,采用简易防护密闭门进行防毒密闭。通过材料试验,结构静、动力模型试验和口部密闭性能试验验证了其可靠性。与过去采用钢筋混凝土预制梁封堵口部的方法相比,本方法抗力更高,密闭性能更加可靠,转换周期更短,封堵构件更轻,具有很高的工程应用价值,为人防工程防护功能的平战转换打下了坚实技术基础。

地下通道施工期复合式衬砌变形特征研究

以武汉市雄楚大街华中师范大学地下通道施工为例,建立了基于荷载结构法的复合式衬砌结构数值计算模型,探究二次衬砌的受力特性。研究结果表明:二次衬砌竖向位移在通道上拱部分呈现由通道中心向两侧方向逐渐增大,下拱部分呈现由通道中心向两侧方向逐渐减小的特征,模拟结果为监测点的布设提供了依据。在充分考虑通道施工过程监测的基础上,提出了对复合式衬砌通道全面有效监测的布设方法。

基于模拟驾驶的立体复合通道安全评价研究

提出了一种基于模拟驾驶的技术,用于高等级立体复合通道的安全评价。首先,实现对复合通道的三维建模和参数化设计,包括主线路段、互通立交及其连接段的几何形态和交通组织信息;然后,结合模拟驾驶技术,通过模拟不同驾驶行为和车辆类型的情景,获取驾驶人的行为特征数据,基于这些数据,可以实现对复合通道的道路安全性进行客观评价和可视化展示;最后,通过一系列试验验证了该方法的有效性和可行性。研究结果表明,基于模拟驾驶的技术在高等级立体复合通道的安全评价中具有重要的应用价值,可为设计者提供科学依据和决策支持。本研究对于高速公路设计和交通安全管理具有重要的理论和实践意义。

基于可持续发展理念的超级工程创新设计

狮子洋跨江复合立体公路通道是粤港澳大湾区跨珠江两岸的又一世界级超级工程,国内首次采用高速公路+城市道路双层(部分路段3层)立体交通方式跨越狮子洋和珠三角核心高度经济发达区与高度城镇化区域,勘察设计中运用可持续发展新理念、按照创新驱动高质量发展新要求开展了系列创新设计与工程实践,为促进大湾区基础设施互联互通、打造国际一流湾区和世界级都市群一体化发展、支撑广州国家综合交通枢纽建设提供了重要交通保障。

复合式通道设计过程数字化应用探索

狮子洋通道工程部分采用双层复合立体结构设计方案,路线方案设计和交通组织十分复杂,需要借助数字化的手段为精细化设计提供帮助。项目从数字化设计入手,通过多维度环境数据与工程模型的集成,完成数字工程的建设,依托数字工程开展设计方案表达、比选、数字“云看线”等应用;借助数字化设计成果同时完成全项目三维净空核对和交通仿真模拟等数字化专项应用工作。项目数字化应用效果显著,相关应用思路和技术路线可为后续同类项目提供有效参考。