超限结构无缝法施工在污水处理工程中的应用

介绍了一种在超限混凝土结构中取消伸缩缝或增大伸缩缝最大间距的新型施工方法——超限混凝土结构无缝法施工。论述无缝法施工的原理及膨胀加强带的设置,探讨UEA膨胀混凝土的配制,在实践的基础上总结了无缝法施工的方法、注意事项及优点。     

高强与高性能混凝土温湿度场应力分析

针对高强与高性能混凝土易于开裂的特点,对高强高性能混凝土早期温湿度场随龄期发展的分布情况以及混凝土的收缩变形进行理论分析,建立相应的计算模型,编制三维有限元程序,分析在外界温湿度变化以及不同养护条件下由混凝土内部温差和湿度变化产生的温度应力和干燥收缩应力,从施工养护方法上探讨了高强与高性能混凝土抗裂性能的改善措施.     

Usage of polystyrene disposable food dishes in the lightweight concrete making

The increasing use and subsequent accumulation of polystyrene containers has triggered a substantial environmental problem. This study investigated using varied percentages of solid waste polystyrene disposable food dishes in the production of lightweight concrete samples with 350 kilograms per cubic meter (kg/m³) of cement and a density of 1,300 kg/m³. The polystyrene disposable dishes were ground into beads of 0–3 millimeters (mm) and 3–6 mm in size. First, the characteristics of Type II Portland cement, polystyrene, and aggregates were examined. The following characteristics of concrete using ASTM International and British Standards Institution standards were tested: slump, compressive strength, ability to resist chloride ion penetration, and resistance of concrete to rapid freezing and thawing cycles. Scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy analytical techniques were also used. The slump of samples varied between 40 and 70 mm and was not dependent on either the polystyrene percentage or the size of the polystyrene beads in the concrete samples (p‐value > .05). The compressive strength of the concrete samples after 90 days of curing, and using different percentages of polystyrene, varied between 96 and 113 kilograms per square centimeter (kg/cm²). The resistance of the samples to the freezing and thawing cycle and chloride ion penetration were affected unfavorably by the presence of the polystyrene. The SEM technique indicated that concrete samples containing 15% and 25% polystyrene had denser crystals and less void than concrete samples with 40% and 55% polystyrene.     

考虑爆裂影响的钢筋混凝土梁火灾温度场数值分析

为了描述混凝土高温爆裂对构件热传导过程的影响,结合钢筋混凝土梁火灾试验,考虑爆裂时间和区域的不确定性,建立了火灾下钢筋混凝土梁数值分析模型,分析爆裂深度、爆裂面积比、爆裂位置等爆裂参数对梁跨中截面温度场的影响规律。研究结果表明:当钢筋混凝土梁发生受火爆裂,梁截面的温度显著升高,并随爆裂深度的增大而进一步增强;爆裂面积比对截面温度场影响不显著,当爆裂深度、爆裂位置一定,爆裂面积比增加达到13%左右时,截面温度场基本上不再变化;爆裂深度、爆裂面积比一定,梁跨中爆裂对截面温度场影响最大,但是底部纵筋处温度较顶部纵筋处温度升高较快。     

基于不同强度等级混凝土的动力学特性研究

基于TAW-2000D电液伺服岩石三轴仪和直径75 mm的霍普金森压杆试验装置,得到了C25,C35和C45混凝土在静、动载荷作用下的应力-应变曲线,探讨了混凝土强度等级、动态峰值强度、峰值应变和应变率之间的变化规律。结果表明:混凝土准静态应力-应变曲线和动态应力-应变曲线在形态上存在明显差异,动态应力-应变曲线的峰值点随应变率的增大向右上方移动,线弹性阶段各曲线斜率变化不明显;动态峰值应力、动态弹性模量和峰值应变均存在不同程度的率相关性,并且混凝土材料的应变率敏感性随其强度等级的提高而增强;混凝土C45的各力学指标对应变率的敏感性最强,C35次之,C25的应变率敏感性最弱;推导了应变率与强度等级和冲击速率之间的经验公式,三者之间存在非线性变化规律。     

用柠檬酸废渣生产蒸压加气砼砌块

本文介绍了用柠檬酸废渣代替天然石膏生产蒸压加气砼砌块，从而解决了长期以来柠檬酸生产厂家因排放柠檬酸废渣所造成的环境污染问题，开创了柠檬酸废渣直接运用的新途径。环境效益和经济效益都较明显。     

混凝土结构可靠度的Monte Carlo模拟

简介了靠度与安全系数的区别；以混凝土结构为例，介绍了用Monte Carlo模拟来计算结构可靠度的方法。     

多孔混凝土及其在生态护坡工程中的应用

多孔混凝土具有连续孔隙,空隙率约为15%～30%,具有良好的透水性和透气性。多孔混凝土生态护坡技术是一种新型的绿色生态型护坡技术,融合建筑材料、生态工程和环境工程等多门学科,集水土保持、生态修复于一体,实现了水利工程护坡技术和生态环境修复技术的完美统一。     

火灾后钢筋混凝土板的承载力计算与可靠指标分析

本文利用有限差分法分析了火灾时钢筋混凝土板内最高温度分布，并根据有关火灾温度后钢筋与混凝土的本构关系及钢筋混凝土结构理论，用数值方法计算了钢筋混凝土板灾后承载能力。此外还根据结构可靠度理论分析了钢筋混凝土板在承受原设计荷载时其可靠指标的变化。     

Environmental life cycle assessment of different types of the municipal wastewater pipeline network

With the onset of social life, humans have considered waste disposal as essential, and they have been able to repel it through brick and clay channels. Checking sewage pipes for energy consumption and a longer lifetime than other sewage system components is important. Climate change and exploitation of industrial resources have made environmental impacts, which are important factors in decision making. The purpose of this study was to introduce the most suitable type of sewage pipe considering environmental protection. Therefore, we applied the environmental life cycle assessment (LCA) method, using Sima Pro 8.2.3 software for the one-kilometer length of concrete pipes (300 mm in diameter), Polyvinyl chloride (PVC), and polyethylene (PE) (315 mm in diameter). Also, the BEES method and sensitivity analysis were used to validate the results. The comparison between three types of municipal wastewater pipes indicated that PE pipes are a more environmentally friendly option than PVC, and concrete pipes in pipe recycling, reducing extraction from untapped resources, and inefficient extraction of resources. Electricity, diesel fuel, and sulfate resistance cement consumption for concrete production are the most pollution elements in the LCA of concrete pipes. Usage of PVC granular, sanitary landfill of PVC pipes, and using hydraulic drill in LCA of PVC pipes are the most elements of generating pollution. The usage of PE granules, PE pipes landfilling, hydraulic excavator, and electricity consumption in the LCA of the PE pipes are the greatest polluting parameters.