玻璃钢筋混凝土的有限元计算与试验

钢筋混凝土广泛应用于土木工程领域，但其结构耐久性因钢筋本身的锈蚀成为现今急待解决的问题。人们一直在寻找对钢筋混凝土进行改良的途径，用玻璃钢筋代替普通钢筋是解决这一问题的一个有效的方法，为此进行了试验和ANSYS有限元分析，结果证明此法具有可行性。     

汽车工业生产用热熔胶膜的研制

介绍了汽车工业生产内装饰复合材料用热熔胶膜的性能及其研制状况。这种热熔胶膜具有使用便捷,高效,生产、使用过程中没有污染的具有热熔胶膜的特长。     

Coordination between strategic forest management and tactical logistic and production planning in the forestry supply chain

In this paper, we study the coordination mechanism in the forestry supply chain between strategic forest management and tactical production planning. We first formulate an integrated model to establish a theoretical benchmark for performance of the entire supply chain. It is a mixed integer programming model that involves harvesting, bucking, transportation, production, and sales decisions for both tactical and strategic planning levels. We then present two sequential approaches S‐A and S‐B where the coordination is done through internal pricing. S‐A is the approach currently used in practice where harvesting in the forest is the main driver of the supply chain activities and internal pricing is introduced to control bucking decision in a separate stage. In contrast, S‐B takes downstream demand information into consideration and internal pricing directly influences harvesting decision in the first stage. In order to find the appropriate setting of internal pricing that leads to the system optimum, we suggest two heuristics H‐I and H‐II. The internal pricing in H‐I is based on dual values and in H‐II, it is derived from a Lagrangian decomposition. A real‐life case study in the Chilean forestry industry is used to compare the results of different approaches. It is shown that the new sequential approach S‐B generates as good feasible solution as that obtained from the integrated approach but in much less time. Both heuristics H‐I and H‐II bring about near‐optimal feasible solutions. H‐II also provides optimistic bound of the optimal objective function value, which can be used as a measure of the solution quality.     

试验温度和停放时间对胶料加工性能的影响

研究试验温度和停放时间对胶料加工性能的影响。结果表明，试验温度对胶料的门尼粘度、门尼焦烧时间和硫化特性均有一定影响。门尼粘度测定的试验温度选择100℃；门尼焦烧时间测定的试验温度一般选120℃，SBR胶料可提高至130℃左右，以缩短试验时间；硫化特性测定的试验温度一般选185℃。试验前模腔达到规定温度后再保持15min，以使转子与模腔温度一致。胶料停放时间应控制在2h左右。     

Photostabilization of cationic UV-cured coatings in the presence of nanoTiO2

The effect of TiO₂ nanoparticles for sun-weathering protection of UV-cured coatings is investigated. TiO₂ is either introduced in the form of nanoparticles in the photocurable formulations or generated in situ via sol–gel process. Cured films containing comparable amounts of TiO₂ were weathered for 800 h under UV irradiation and compared with free-TiO₂ coating. The TiO₂ presence induces a clear lower mass loss decrease during weathering as well as a lower gel content decrease. The TiO₂ screen effect is also confirmed by a lower alkyl-band reduction monitored by FT-IR during weathering. The TiO₂ generated in situ via sol–gel gives rise to transparent coatings without interfering with photopolymerization process and therefore without compromising UV-cured film properties.     

Effects of apitong (Dipterocarpus spp.) extractives on bond strength development and curing rate of adhesives

Emulsion polymer isocyanate ( ), polyvinyl acetate ( ) and resorcinol-formaldehyde ( ) adhesives were used to produce single lap shear specimens using resinous and non-resinous apitong (Dipterocarpus spp.) timbers. Tests showed that joints made with highly resinous apitong were about 40% weaker than similar joints made with non-resinous apitong. The resinous apitong was treated with different solvents to yield five different extractives which were characterized by infra-red analysis. Apitong extractives were then added to and adhesives and joints made with buna (Fagus crenata), a timber known to be low in extractives and easy to bond. Joints prepared using extractive-containing adhesives were generally weaker than those made with the unmodified adhesives. RF adhesives containing extractives cured more slowly than unmodified . It is thought that the acidic nature of the extractives changes the pH of the system sufficiently to affect the curing mechanism     

型钢翼缘狗骨式削弱在型钢混凝土节点的作用

为了防止地震时型钢混凝土节点核心区发生剪切破坏以及梁柱连接焊缝发生脆性断裂,提出对型钢混凝土节点核心区附近梁端型钢的上、下翼缘采取狗骨式削弱,并系统研究翼缘削弱对提高型钢混凝土节点抗震性能的作用.研究表明,由于在梁端型钢翼缘采取狗骨式削弱,不仅能够将塑性铰控制在梁型钢削弱的位置,从而有效地降低了节点核心区所受的剪力以及梁柱连接焊缝的应力;而且能够改善节点塑性铰区的转动能力和抗剪性能,提高节点的延性和耗能能力.     

双洞口配筋砌块砌体框支墙梁试验

为研究双洞口配筋砌块砌体框支墙梁地震前后的受力模式,在拟动力子试验前后进行了底层框架配筋砌块短肢砌体剪力墙结构三层足尺模型的竖向力静载试验.试验结果表明:托梁与上部墙体表现出良好的协同工作能力,其工作模式为拉杆拱.通过对其在拟动力试验前后的受力模式进行了比较,可知带洞口配筋砌块砌体框支墙梁结构体系在墙体受到一定损伤时,并不会使墙梁的受力机理发生明显改变.     

CFRP加固钢筋混凝土梁滞后应变计算方法

为了系统研究从零负载状态到满负载状态各个阶段CFRP片材加固梁滞后应变的计算方法,在充分考虑加固梁不同负载状态及受压区混凝土非线性本构关系的基础上,分别建立了不同负载贴片加固梁考虑混凝土抗拉作用时的滞后应变计算公式及不考虑混凝土抗拉作用时的简化计算公式.试验数据和对比分析结果表明:"考虑混凝土抗拉作用"公式的计算结果与试验数据吻合良好,计算误差<8%,明显优于现有文献的计算方法;"不考虑受拉区混凝土抗拉作用"公式的计算结果在混凝土开裂前和试验值相差较大,但对已裂加固梁的计算误差与"考虑混凝土抗拉作用"公式的计算误差接近.为简化计算,对未裂和已裂混凝土梁贴片加固时的滞后应变可分别采用"换算截面"公式和"不考虑混凝土抗拉作用"公式进行计算,两种简化方法的误差均不会超过10%.     

S-P混杂纤维对混凝土长期性能与耐久性影响

采用对比的试验方法,研究并讨论了钢纤维、聚丙烯纤维及其混杂对混凝土长期性能及耐久性的影响.研究结果表明,用不同尺度、不同性质的钢纤维与聚丙烯纤维按二元混杂以总体积率0.9%掺入高性能混凝土中,明显改善了水泥混凝土的长期性能,90d干缩值减少36.6%,200d徐变度降低45.4%,并可显著提高混凝土的耐久性能,相对渗透系数降低79.03%,氯离子渗透系数降低30.5%.