Repair of Slab–Column Connections Using Epoxy and Carbon Fiber Reinforced Polymer

Repair, strengthening, and retrofit of reinforced and prestressed concrete members have become increasingly important issues as the World’s infrastructure deteriorates with time. Buildings and bridges are often in need of repair or strengthening to accommodate larger live loads as traffic and building occupancies change. In addition, inadequate design and detailing for seismic and other severe natural events has resulted in considerable structural damage and loss of life, particularly in reinforced concrete buildings. Numerous buildings and bridges suffer damage during such events and need to be repaired. The use of carbon fiber reinforced polymer (CFRP) composite fabric bonded to the surface of concrete members is comparatively simple, quick and virtually unnoticeable after installation. The use of composites has become routine for increasing both the flexural and shear capacities of reinforced and prestressed concrete beams. Earthquake retrofit of bridge and building structures has relied increasingly on composite wrapping of columns, beams and joints to provide confinement and increase ductility. This paper presents the results of cyclic testing of three large-scale reinforced concrete slab–column connections. Each of the specimens was a half-scale model of an interior slab–column connection common to flat-slab buildings. The specimens were reinforced according to ACI-318 code requirements and included slab shear reinforcement. While supporting a slab gravity load equivalent to dead load plus 30% of the live load, the specimens were subjected to an increasing cyclic lateral loading protocol up to 5% lateral drift. The specimens were subjected to the same loading protocol after they were repaired with epoxy crack sealers and CFRP sheet on the surfaces of the slab. Repair with epoxy and CFRP on the top surface of the slab was able to restore both initial stiffness and ultimate strength of the original specimen.     

闭口压型钢板-轻骨料屋面板抗弯试验研究

结合闭口压型钢板-轻质混凝土组合板的应用现状,阐述了该新型屋面结构的优点,通过试验对其抗弯刚度性能进行了研究,并总结了抗弯刚度的理论计算公式,得出计算结果与实测值吻合较好的结论.     

闭口式压型钢板-混凝土组合楼板受剪承载力试验研究

进行了 6块闭口型组合楼板的受剪试验 ,获得了其斜截面抗剪承载力及破坏形式 ,提出了这种组合板斜截面抗剪承载能力的简化计算公式 ,供工程设计时参考。试验结果与计算值的比较表明 ,简化计算公式能较合理地估算这种闭口型组合楼板的抗剪承载力     

陕西省信息大厦超高层结构设计和安全性分析

陕西省信息大厦结构设计有以下特点:(1)是目前国内8度抗震设防地区最高的超限高层钢筋混凝土组合简体结构,主楼高189.4m;(2)国内首次在黄土地区采用68m长的超长钻孔灌注桩;(3)为减少建筑物高度,7～48层采用部分无粘结预应力混凝土板结构;(4)进行了结构弹塑性分析,包括静力推覆(Pushover)分析和动力反应时程分析。     

预应力混凝土叠合空心楼板的受剪性能试验研究

结合现浇空心楼盖与叠合楼盖的优点,提出在一种新型预应力叠合楼板中布置筒芯内模以形成叠合空心楼板。进行了3组共10块模型板带的板端抗剪试验,根据实测试件的荷载位移曲线、受剪承载力及板中箍筋应变变化情况,研究了筒芯内模布置方式、预制底板形式、抗剪箍筋、肋梁及顺筒肋对叠合空心板受剪性能和自然粗糙叠合面粘结强度的影响。研究结果表明:顺筒布置的叠合空心板抗剪承载力高于横筒布置的对比试件;预制带肋底板的预制纵肋能有效提高叠合空心试件的抗剪性能和叠合面水平抗剪强度;无论筒芯布置方式和预制底板形式如何变化,叠合层混凝土与预制底板的叠合面粘结强度均满足水平抗剪要求;依据试验结果,提出了考虑不同混凝土强度等级、叠合面高度、肋梁和顺筒肋影响的叠合空心板受剪承载力计算方法。     

Multiple scattering of shear waves and dynamic stress from a circular cavity buried in a semi-infinite slab of functionally graded materials

Based on the theory of elastodynamics and employing image method, the multiple scattering and dynamic stress in a semi-infinite slab of functionally graded materials with a circular cavity are investigated. The analytical solution of this problem is derived, and the numerical solutions of the dynamic stress concentration factor around the cavity are also presented. The effects of the distance between the cavity and the boundaries of the semi-infinite slab, the incident wave number and the non-homogeneity parameter of materials on the dynamic stress concentration factors are analyzed. Analyses show that the dynamic stress around the cavity increases with increasing non-homogeneity parameter of materials and incident wave number. The boundaries of the semi-infinite slab have great effect on both the maximum dynamic stress and the distribution of dynamic stress around the circular cavity, and the effect increases with increasing incident wave number.     

Application of Suspension Bridges Stiffened by Prestressed Concrete Slabs in China

Four suspension bridges stiffened by prestressed concrete slabs were designed and constructed on highways in southwestern mountainous areas of China. These bridges are the first applications of its kind in China. This paper discusses the site condition, adaptability, and design and construction features of these bridges. These bridges have single suspension spans between 278 and 388?m and deck width between 14.4 and 15.0?m. The longitudinal distance between hangers is only 5?m, which is relatively small for this bridge type, and there are only two lanes. The dual direction prestressed concrete slabs are 0.6?m deep, and its wind blocking area is relatively small. Dynamic analysis and wind tunnel tests verify that the wind resistance requirements are easily satisfied.     

压型钢板—混凝土组合楼板剪切粘结承载力试验研究

组合楼板作为一种新型的楼板结构形式被日益广泛地采用。其破坏模式主要有弯曲破坏与剪切破坏。本文针对剪切破坏的主要破坏模式纵向水平剪切粘结破坏。通过理论与实验两方面进行研究 ,并针对我省常用的板型 YX- 76- 34 4- 6 88提出组合楼板的纵向水平抗剪公式 :Vubh0=134 .3ρh0L′+0 .0 44 fc以为我省组合楼板的应用提供参考。     

CFRP Strengthening for Punching Shear of Interior Slab–Column Connections

This paper presents the results of an experimental investigation studying the effect of retrofitting interior slab–column connections against punching shear failure with externally bonded carbon fiber reinforced polymer (CFRP) strips. Six full-scale, 2000?mm-square×150-mm-thick slab specimens were constructed. The effect of varying the CFRP strengthening amount and configuration on the load-carrying capacity of the slab specimens was investigated. Specimens were supported along their edges and tested to failure. Strengthened slabs showed an increase in stiffness between 29 and 60% and in punching capacity between 6 and 16% with respect to the control unstrengthened slab. An analytical model was refined to predict the punching shear capacity of the specimens strengthened with CFRP strips. The model takes into account both the configuration and amount of CFRP strips. The proposed model shows good agreement with the experimental results.     

一种新型道路结构与材料的研究

本文考虑以工业废渣为主要原料生产的一种高抗折道路水泥 ,水泥熟料用量小于 2 5 % ,其耐磨性能、抗侵蚀性能、抗干缩变形等性能十分优良 ,特别是抗折强度高 ,可作为道路水泥换代产品。同时考虑采用圆形中空板 ,按文克尔弹性地基板模型 ,引入温度应力假设 ,对新型结构路面板进行有限元分析 ,结果表明 :其强度、疲劳均能较好满足重级和特重级别情况下的使用要求 ,而混凝土用可节约 2 0 %～ 30 %。