粘钢加固钢筋混凝土梁的受力机理

本文通过对四根粘钢加固钢筋混凝土梁的单调加载静力试验,测得了粘钢中固梁的纵向受力钢筋,受拉粘钢底板,粘钢侧板,粘钢箍板及受压区混凝土的应变和梁的挠度等数据。并通过理论分析计算了粘钢加固梁的正截面承载力,斜截面承载力及刚度,挠度等,通过试验和理论计算,探讨了粘钢加固梁的受力机理,分析了有效的加固方案,并对炽钢另固钢筋混凝土梁的合理设计提出了一些建议。     

粘钢加固钢筋混凝土梁斜截面承载能力的试验研究

通过10根外部粘钢加固钢筋混凝土梁的斜截面抗剪试验,研究了外贴U型钢板、梁侧竖直钢板、梁侧斜钢板和梁侧钢丝网对梁的加固效果.试验结果表明:梁侧钢板角度对粘钢加固效果有明显的影响,采用45°斜向粘钢效果最好;由于锚固长度较短,易产生锚固破坏,应用时必须采取可靠的附加锚固措施;外部粘贴钢丝网无论是对提高抗裂能力还是承载能力都有明显的效果.通过理论分析,提出了粘钢加固梁斜截面的抗剪计算公式,与试验值吻合较好.     

不同卸荷和钢种对粘钢梁抗弯极限值的影响

论述了当钢筋混凝土梁采用粘钢加固时，完全卸荷、不卸荷粘钢以及外粘钢板为不同钢种时，对粘钢梁正截面抗弯承载力极限值的影响程度。     

混凝土梁卸荷后斜向粘钢加固抗剪承载力计算

混凝土梁斜截面粘钢加固是工程中经常遇到的问题 ,在结构试验的基础上 ,给出了斜粘钢板的最佳锚固方式及开裂后卸荷斜粘钢板抗剪承载力计算方法 ,可供工程加固计算时参考。     

粘钢加固混凝土梁受剪性能试验研究

通过对11个普通钢筋混凝土（RC）梁试件及4个部分预应力混凝土（PPC）梁试件采用U形钢板箍加固的抗剪试验和数值分析,研究不同损伤程度、剪跨比、配箍率、钢板箍间距、预应力水平、钢板厚度等因素对粘钢加固混凝土梁受剪性能的影响。结果表明：采用U形钢板箍对RC梁进行抗剪加固能够有效抑制斜裂缝的开展,提高加固梁斜截面受剪承载能...     

钢筋混凝土梁受弯加固对比试验研究

通过钢筋混凝土矩形截面梁的抗弯测试,对用碳纤维布补强和钢板粘接加固的钢筋混凝土梁进行了抗弯性能对比试验研究,分析了碳纤维和粘钢加固钢筋混凝土梁抗弯性能的主要影响因素。计算结果与试验数值吻合较好,得到了两种加固方法的适用性设计指标。     

粘钢及增大截面加固预应力梁的抗弯承载力计算

粘钢及增大截面,对梁的受拉薄弱区进行补强,是梁常用的加固方式。对于两种加固方法同时采用的预应力混凝土梁,其抗弯承载力则需新的理论公式验算。根据预应力钢筋混凝土梁的抗弯承载力计算原理,对其计算方法进行了理论推导,并通过一双筋矩形截面试验梁来验证这一理论,得出粘钢及加大截面加固法能有效提高梁的抗弯承载力的结论。     

侵蚀环境与荷载耦合作用下钢筋混凝土梁斜截面承载力试验

通过室内模拟试验,研究混合侵蚀溶液、冻融循环与持续荷载耦合作用下,钢筋混凝土梁斜截面承载力和刚度退化、斜截面破坏形态等规律。试验结果表明,预加载比例对侵蚀和冻融环境下钢筋混凝土梁斜截面承载力影响明显,梁的刚度和延性退化程度与箍筋锈蚀和剪压区混凝土劣化有关。最后,给出混合侵蚀、冻融与持续荷载耦合作用下钢筋混凝土梁斜截面承载力计算方法。     

外粘整块钢板加固钢筋混凝土梁受剪试验研究

通过 1 1根混凝土强度等级为C1 4的简支梁试件在集中荷载作用下的试验研究 ,得到外粘整块钢板后梁的受剪承载力。随粘钢规格的不同 ,粘钢混凝土梁发生不同的破坏形态。根据试验结果 ,建立了粘钢部分承担的受剪承载力理论计算公式和受剪斜截面限制条件。     

粘钢加固法加固钢筋混凝土梁的数值模拟研究

为研究粘钢加固后钢筋混凝土梁的受力性能变化,采用ABAQUS有限元程序对钢板加固的矩形截面钢筋混凝土梁和未加固梁进行了非线性有限元数值模拟计算,计算结果表明:钢板加固后的钢筋混凝土梁截面符合平截面假定,且与未加固梁相比,具有更高的极限承载力和刚度。     

Strengthening of RC beams in shear using GFRP inclined strips – An experimental study

Though there have been a number of studies on shear strengthening of RC beams using externally bonded fiber reinforced polymer sheets, the behaviour of FRP strengthened beams in shear is not fully understood. This is partly due to various reinforcement configurations of sheets that can be used for shear strengthening and partly due to different failure modes a strengthened beam undergoes at ultimate state. Furthermore, the experimental data bank for shear strengthening of concrete beams using FRP remains relatively sparse due to which the design algorithms for computing the shear contribution of FRP are not yet clear. The objective of this study is to clarify the role of glass fiber reinforced polymer inclined strips epoxy bonded to the beam web for shear strengthening of reinforced concrete beams. Included in the study are effectiveness in terms of width and spacing of inclined GFRP strips, spacing of internal steel stirrups, and longitudinal steel rebar section on shear capacity of the RC beam. The study also aims to understand the shear contribution of concrete, shear strength due to steel bars and steel stirrups and the additional shear capacity due to glass fiber reinforced polymer strips in a RC beam. And also to study the failure modes, shear strengthening effect on ultimate force and load deflection behaviour of RC beams bonded externally with GFRP inclined strips on the shear region of the beam.     

Rehabilitation of rectangular simply supported RC beams with shear deficiencies using CFRP composites

The present study examines the shear performance and modes of failure of rectangular simply supported reinforced concrete (RC) beams designed with shear deficiencies. These members were strengthened with externally bonded carbon fiber reinforced polymer (CFRP) sheets and evaluated in the laboratory. The experimental program consisted of twelve full-scale RC beams tested to fail in shear. The variables investigated within this program included steel stirrups, and the shear span-to-effective depth ratio, as well as amount and distribution of CFRP. The experimental results indicated that the contribution of externally bonded CFRP to the shear capacity was significant. The shear capacity was also shown to be dependent upon the variables investigated. Test results were used to validate a shear design approach, which showed conservative and acceptable predictions.     

粘贴预应力GFRP板-混凝土梁抗剪加固试验研究

先通过预张玻璃钢板(Glass-Fibre-Reinforced-Polymer,简称GFRP)粘贴于混凝土梁受拉面,后在梁侧面用GFRP板进行剪切补强试验;分析了不同侧面贴GFRP方式对加固梁抗剪性能和破坏模式的影响,比较了各试验梁的跨中挠度、力筋和GFRP板应变的关系.试验结果表明,侧面贴GFRP可有效抑制斜裂缝的出现,提高试验梁的抗剪能力,改变其破坏形态,加固效果比较理想.     

Shear strengthening of RC beams with web-bonded continuous steel plates

This paper presents the results of an experimental program and a parametric study conducted on RC beams strengthened in shear with web-bonded continuous steel plates. An experimental investigation was conducted to assess the effectiveness of web-bonded continuous steel plates for shear strengthening of RC beams having internal stirrups. A two-dimensional nonlinear finite element model was developed to simulate the overall behavior of beams with epoxy bonded steel plates. In order to develop a design methodology for beams with web-bonded steel plates, a parametric study was conducted. Main parameters considered were concrete strength, plate thickness, plate depth-to-beam depth ratio, yield strength of steel plates, beam size and the internal shear reinforcement ratio. A formula to compute the shear strength of such beams was proposed by adding up the concrete contribution, shear reinforcement contribution and the contribution of steel plates. The validity of proposed formula was checked against the results from parametric study and the experiments. It was found that the proposed formula predicts the ultimate shear strength of RC beams with web-bonded continuous steel plates very well.     

织物增强混凝土加固RC梁的斜截面抗剪承载力试验研究

基于不同剪跨比的织物增强混凝土(TRC)加固RC梁的斜截面抗剪承载力试验,研究被加固梁的斜截面抗剪承载力及其破坏形态的变化,并研究剪跨区加固后梁的变形特点。试验结果表明,加固措施可以有效地提高梁的斜截面抗剪承载力,改善梁的斜截面破坏的脆性,对斜裂缝的发展有一定的约束作用,并减小梁在斜裂缝出现前的挠度。试验还表明,对剪跨比较大的RC梁,采用织物增强混凝土薄板加固后,其斜截面抗剪承载力提高幅度较大:当剪跨比为1时,加固后梁的斜截面极限抗剪承载力提高4%;当剪跨比为2.5时,加固后梁的斜截面极限抗剪承载力提高68%。在试验研究的基础上,给出TRC薄板加固梁的受剪承载力设计计算公式,公式计算结果与试验结果基本吻合。     

侧立面嵌贴碳纤维增强塑料板条加固混凝土梁受剪承载力研究

为研究加固钢筋混凝土梁的受剪承载力,按照沿梁轴向非对称布置箍筋的方式浇筑13根钢筋混凝土梁试件,在箍筋布置较少侧混凝土梁侧立面保护层上嵌入或外贴碳纤维增强塑料板条对混凝土梁进行受剪切补强。对其进行弯曲试验,研究内嵌碳纤维增强塑料板条补强混凝土梁的破坏形态、承载力等情况,并与相应位置外贴等量碳纤维增强塑料板条的混凝土梁进行比较,分析内嵌或外贴在混凝土梁上的碳纤维增强塑料板条应变变化情况及补强混凝土梁受剪承载力影响因素和受剪承载力计算方法。研究表明,与对比梁相比,内嵌碳纤维增强塑料板条补强混凝土梁受剪承载力提高18.8%~45.8%,外贴碳纤维增强塑料板条补强混凝土梁受剪承载力提高12.5%~13.3%,提出的承载力计算式计算结果与试验值吻合较好。     

RC beams shear-strengthened with FRP: Stress distributions in the FRP reinforcement

Reinforced concrete (RC) beams may be strengthened for shear with externally bonded fibre reinforced polymer (FRP) composites through complete wrapping, U-jacketing or bonding on their sides only. The two main shear failure modes of such strengthened beams are FRP rupture and debonding. In both modes of failure, the contribution of the bonded FRP reinforcement to the shear capacity of the beam depends strongly on the stress (or strain) distribution in the FRP at the ultimate limit state. This paper presents a numerical study of the FRP stress distribution at debonding failure in U-jacketed or side-bonded beams using a rigorous FRP-to-concrete bond–slip model and assuming several different crack width distributions. Numerical results indicate that Chen and Teng’s early simple assumption [Chen JF, Teng JG. Shear capacity of FRP-strengthened RC beams: FRP debonding. Constr Build Mater 2003;17:27–41] for the stress distribution in the FRP results in satisfactory predictions for the effective FRP stress in most cases for both U-jacketed and side-bonded beams. However, it may become unconservative for side-bonded beams that have only light flexural steel reinforcement.     

复合材料设计中SPSW和CSPSW的周期性质

剪力墙系统常用于高层建筑结构中抵抗侧向荷载。复合钢板剪力墙(CSPSW)系统具有承载力高、延展性好、耗能能力强等特点,越来越多的用于钢结构中以抵抗侧向荷载。介绍了钢板剪力墙(SPSW)和复合钢板剪力墙(CSPSW)的相关试验。对两个1/3缩尺抛光试样进行焊接和测试,试验剪力墙系统由混凝土填充圆形中空截面(CHS)钢管柱、钢梁和SPSW或CSPSW组成。对试验结果进行分析和总结,结果显示SPSW和CSPSW系统具有良好的延展性和耗能能力。SPSW系统主要用于抵抗侧向荷载作用下薄壁钢板屈曲产生的薄膜张力引起的层间剪力。CSPSW系统中附加在钢板两侧的混凝土加固(RC)镶嵌板主要用于确保复合材料的性能,防止钢板屈曲。与SPSW系统相比,CSPSW系统的承载力和耗能能力显著增强。     

Cyclic behavior of SPSW and CSPSW in composite frame

Shear wall systems are one of the most commonly used lateral-load resisting systems in high-rise buildings. The composite steel plate shear wall (CSPSW) systems have strong points, such as high bearing capacity, good ductility and energy dissipation capacity, which have been increasingly used as lateral load-resisting system in steel buildings. This paper describes the experimental work related to the tests of steel plate shear wall (SPSW) system and CSPSW system. Two 1/3 scaled specimens were fabricated and tested. The tested shear wall system consisted of concrete-filled circular hollow section (CHS) steel columns, steel beams, and SPSW or CSPSW. The experimental results were summarized and discussed, which showed that both SPSW system and CSPSW system possessed good ductility and energy dissipation capacity. For SPSW system, the primary mechanism for resisting storey shear arising from lateral loads came from the post-buckling inclined tension field that forms for thin-walled steel plate. For CSPSW system, the reinforced-concrete (RC) panels attached on both sides of steel plates were able to ensure the composite action by preventing the overall buckling of steel plate. Compared with SPSW system, the bearing capacity and energy dissipation capacity of CSPSW system increased evidently.