Stahlbeton‐Verbundkonstruktionen – Ein Bemessungskonzept für schubbeanspruchte Fugen. Teil 1: Korrelation zwischen Simulation und Bemessung

R/C Composite Constructions – A Design Concept for Shear Loaded Joints – Part 1: Correlation between Simulation and Design. In the modern engineering practice composite constructions are often used. This constructions consisting of prefabricated R/C components and in situ concrete are marked by the interaction of concrete interfaces with different age and different strength. With various examinations will be show, that the present designing practice and the distribution of reinforcement is not effective and leads to high reinforcement concentrations in uncritical joint sections and also to an unbalanced reinforcement along the joint. This paper is divided into 2 parts: Part 1 summarizes the state‐of‐the‐art, a special structural model and important results. A design concept, continued in part 2, will be presented for the practical use according to European standard EC 2, which enables the differentiation between narrow and broad bond surfaces for the first time. Additional, the new concept considers the non‐rigid bond and also decisive parameter in a subtly differentiated, nearly realistic and bearing structure referred way.     

Stahlbeton‐Verbundkonstruktionen – Ein Bemessungskonzept für schubbeanspruchte Fugen. Teil 2: Normative Empfehlungen für Neubau und Revitalisierungsmaßnahmen

R/C Composite Constructions – A Design Concept for Shear Loaded Joints – Part 2: Normative Recommendations for New Building and Retrofit Measures In the modern engineering practice composite constructions are often used. This constructions consisting of prefabricated R/C components and in situ concrete are marked by the interaction of concrete interfaces with different age and different strength. With various examinations will be show, that the present designing practice and the distribution of reinforcement is not effective and leads to high reinforcement concentrations in uncritical joint sections and also to an unbalanced reinforcement along the joint. This paper is divided into 2 parts: Part 1 summarizes the state‐ofthe‐ art, a special structural model and important results. A design concept, continued in part 2, will be presented for the practical use according to European standard EC 2 which enables the differentiation between narrow and broad bond surfaces for the first time. Additional, the new concept considers the non‐rigid bond and also decisive parameter in a subtly differentiated, nearly realistic and bearing structure referred way.     

再生混凝土框架梁柱中间节点试验研究

对6个再生混凝土框架梁柱中间节点足尺构件进行低周反复荷载试验,研究低轴压比条件下再生混凝土节点区的粘结锚固性能。通过改变穿越节点核心区的梁纵筋直径、强度来研究再生混凝土节点的最小相对锚固长度,同时研究新的构造措施对节点粘结锚固性能及核心区抗剪能力的影响。结果发现在低轴压比条件下,按照普通混凝土规范设计的再生混凝土框架梁柱中间节点发生粘结滑移破坏,减小梁纵筋直径或在贯穿节点区的梁纵筋上焊接横向锚固钢筋均可以提高节点区的粘结锚固性能。再生混凝土节点抗剪承载力应在普通混凝土节点计算公式的基础上进行折减。     

钢筋砼空间框架节点抗震性能的研究

本文提供了12个钢筋砼空间框架节点在双向反复荷载作用下的试验研究结果,其主要的研究参数是柱梁抗弯强度比值、约束构件尺寸(梁与板)、节点配筋、柱轴向力以及加荷过程。对节点的滞回特性和通过节点的梁筋与柱筋的滑移也进行了研究。在试验结果的基础上,提出了在地震型荷载作用下空间框架节点的设计建议,其中包括柱梁抗弯强度的最小比值、约束梁梁宽与柱宽的最小比值、节点抗剪强度的计算方法以及梁纵向钢筋在节点内的最小锚固长度。     

Shear strength estimation of reinforced concrete beam–column sub‐assemblages using multiple soft computing techniques

The aim of the present study is to propose innovative predictive models for shear capacity of reinforced concrete (RC) exterior joints in terms of multiple soft computing techniques. Existing models were evaluated and by a preliminary sensitivity analysis, seven parameters including compressive strength of concrete, product of the yield stress and the reinforcement ratio of the joint stirrups, the effective width of the joint panel, cross‐sectional column width, beam tensile longitudinal reinforcement ratio, beam compressive longitudinal reinforcement ratio, and column longitudinal reinforcement ratio were considered. Then, a large data set having the details of experimental programs on shear capacity of exterior RC beam–column joints was provided. The experimental data were utilized in developing the proposed models. After verification of the new models against available database, their efficiency compared with existing models was confirmed. Finally, a sensitivity analysis was performed in order to find the relative importance of each input parameter on the shear strength of RC joints. The results indicated that the beam reinforcement is the most important factor in shear capacity estimation of exterior RC beam–column connections.     

Stützen‐Deckenknoten für Schleuderbetonstützen

Column‐Slab Joints for Spun Concrete Columns In this paper joints consisting of high capacity spun concrete columns with reinforcement ratios up to 14,7% and slabs made of normal strength concrete are discussed. The main focus was put on the load transfer from the columns through the concrete slab. In all tests the reinforcement of the columns in the joints was not continuous. For spun concrete columns an optimized solution using a high strength core is presented. The conventional joints and the joints using a high strength core are compared in experimental tests. The results showed that the new joint design is capable of transferring higher loads and reduce the deformations in the slab. On the basis of the experimental data a model was developed, which provides simple design equations for such joints.     

高强钢绞线网加固混凝土粘结性能试验研究

通过高强钢绞线网聚合物砂浆加固层与混凝土结构的剥离破坏试验,对加固层与混凝土界面的剥离破坏特征进行了研究。探讨了单侧加固、植筋加固及U型加固等不同的加固方式对加固层抗剪承载力及抗剪强度的影响。试验结果表明,采用U型加固等增加粘结面积的方式能有效提高加固层粘结面抗剪承载力,但同时会削弱加固层的抗剪强度,而在界面上植入抗剪钢筋后,能同时提高聚合物砂浆加固层的抗剪承载力及抗剪强度。根据试验结果,提出了最小植筋率的建议值。     

Einführung in die Neuausgabe von DIN 1045-1

Introduction in the New Edition of DIN 1045-1 Resulting from editing of the National Annex of the new European design standard for concrete structures Eurocode 2 and under consideration of experiences with the use and interpretation of the German design standard a consolidated new edition of DIN 1045-1 is published in 2008. In this paper the changes and their backgrounds in the new edition of DIN 1045-1 are explained. This paper will clarify the new or changed rules for – the moisture classes because of alkali-silica-reaction (ASR) – the concrete cover – the effective creep coefficient – the temperature intervals for steel characteristics – the minimum shear resistance – the shear interfaces – the increase of shear for punching at wall-end and -corner – the reinforcing steel fatigue characteristics – the crack width limiting minimum reinforcement for thick members – the transverse reinforcement in the lap zone and at columns – the ductility reinforcement     

Mit Schrauben Bewehren – Neue Ergebnisse

Self‐tapping screws as reinforcement – new results. Self‐tapping continuously threaded screws can be used as elements for reinforcement or joints in timber construction because of their high axial strength and excellent bonding properties. The layout of the reinforcing or joining screws can be derived from strut‐and‐tiemodels which are common in concrete design and follow the internal flow of forces. Several series of tests in 2007 already showed the high potential of this construction method on various joint details and reinforced timber elements. Based on this success in 2008 further tests were taken out on joints and timber beams with altered and more sophisticated screw configurations. Hereby the load‐bearing capacity of timber beams reinforced with steel lamellas and rigid frame corners connected with self‐tapping screws was extraordinary and demonstrated once more the high potential of this design method.     

钢筋混凝土框架夹心节点抗震性能试验研究

钢筋混凝土框架结构中通常柱混凝土强度高于梁的混凝土强度,当节点与梁用较低强度混凝土同时浇筑时,便形成钢筋混凝土框架夹心节点。通过11个钢筋混凝土框架夹心节点（包括平面中节点2个,平面端节点2个,改进型平面节点4个,空间中节点、空间端节点、空间角节点各1个）及3个用于对比分析的传统空间节点（空间中节点、空间端节点、空间角节点各1个）的拟静力试验,结合之前完成的7个平面夹心节点试验及6组平面夹心节点与传统节点的抗震性能对比,对钢筋混凝土框架夹心节点的抗震性能进行研究,包括开裂损伤过程、失效模式、位移延性、变形性能、受压承载力、受剪承载力、滞回耗能、梁筋粘结锚固性能等。研究表明：虽然核心区混凝土强度降低对试件抗震性能有一定不利影响,但通常不会改变框架节点的破坏模式,满足剪压比、轴压比、梁柱混凝土强度比、核心区配筋量条件下的夹心节点,其抗震性能大多可以满足结构设计的需求,或采取加插短筋、增设斜筋等加强措施后可以满足。     

型钢混凝土柱-混凝土梁混合节点抗震性能试验研究

为了研究强节点系数对型钢混凝土(SRC)柱-混凝土(RC)梁混合节点破坏形态的影响,对6个SRC柱-RC梁混合节点开展低周反复荷载试验。通过调整梁端纵筋配筋率和节点箍筋配置以构造不同的强节点系数,实现SRC柱-RC梁混合节点梁端弯曲破坏、梁端弯曲-节点剪切破坏和节点剪切破坏3种不同的破坏模式。在试验研究基础上,考察该类混合节点的滞回曲线、骨架曲线和各受力阶段变形特性。研究结果表明,强节点系数是控制SRC柱-RC梁混合节点破坏形态的重要参数,强节点系数小于1.1时,一般发生节点剪切破坏,应通过合理设计加以避免;由于柱型钢穿越节点核心区,增强了对核心区混凝土的约束,使得SRC柱-RC梁混合节点发生节点剪切破坏后的受力性能优于RC节点;通过对试验数据的分析,提出SRC柱-RC梁框架结构满足四个抗震性能水平的位移角限值。     

钢纤维活性粉末混凝土梁柱中节点抗震性能试验研究

为研究钢纤维活性粉末混凝土梁柱中节点的抗震性能及受剪承载力,完成了8个钢纤维活性粉末混凝土梁柱中节点试件的拟静力试验,研究了钢筋强度、节点核心区配箍率、贯通节点的腰筋及柱内非角部钢筋对活性粉末混凝土梁柱中节点的破坏过程、破坏形态、受剪承载力、滞回特性、耗能、承载力和刚度退化等抗震性能的影响。结果表明,梁柱纵筋采用HRB600高强钢筋延缓了刚度退化速率,提高了试件的耗能能力;核心区箍筋配筋率的增大能够改善破坏阶段试件的承载力退化特性和耗能能力,节点核心区横向钢筋面积率为0~0.98%时,节点的受剪承载力和延性随横向钢筋面积率的增大而增大;贯通节点的梁内腰筋和柱内非角部钢筋均能够有效提高节点受剪承载力、延缓构件承载力的退化、提高其耗能能力。采用GB 50011—2010《建筑抗震设计规范》的受剪承载力公式,对于低配箍率节点承载力计算偏于保守,当面积配箍率大于0.98%时偏于不安全;ACI 352-02中公式的计算结果与试验值更接近,约有9%~46%的安全裕度。     

钢筋混凝土异形柱框架节点强度的研究

对１２个异形柱（Ｔ形、Ｌ形和十形）和４个矩形柱的足尺板柱节点和梁柱节点试件进行了反复荷载作用下受力过程和破坏特性的试验研究及分析对比。研究表明：在板的正常配筋条件下板柱节点是不会破坏的;四种截面形式柱中Ｌ形截面柱节点的承载力是最低的。通过试验和非线性有限元分析,对异形柱框架梁柱节点的强度提出了计算公式,计算结果和试验结果吻合较好。     

混凝土受弯构件受拉钢筋最小配筋率

简述了中国不同时期的混凝土设计规范对非抗震情况和抗震情况下受拉钢筋最小配筋率的取值及确定原则,同时对比分析了各国混凝土设计规范中2种情况下混凝土受弯构件受拉钢筋最小配筋率的规定及确定方法;通过实例对各国规范的最小配筋率取值进行了比较,建议了最小配筋率的确定原则。结果表明:各国规范多以"截面开裂后,构件不致立即失效"为确定最小配筋率的原则,但对非抗震构件所取的最小配筋率相差较大,对抗震区最小配筋率的取值,除中国规范偏低外,其他国家规范大体相当。     

钢管混凝土斜柱抗剪环-环梁节点受力性能试验研究

进行了7个按实际工程2∶3比例缩尺、75°倾斜的钢管混凝土斜柱抗剪环-环梁节点试验。其中5个试件采用单调方式加载,2个试件采用低周反复方式加载。试验过程中,对环梁截面上、下环筋,环梁箍筋以及纵梁纵筋的应变分布及大小进行了量测,记录了试件的荷载-位移曲线。改变试件环梁环筋与纵梁纵筋的比例,改变环梁箍筋形式及加配特殊构造钢筋等措施,对斜柱抗剪环-环梁节点的宏观受力机理、最终破坏形态、受力性能及其影响因素等进行了分析研究。试验结果表明,通过对环梁合理配筋构造,抗剪环-环梁节点能够有效地传递框架梁端的弯矩和剪力;无论最终破坏发生在框架梁端还是环梁内,试件都能达到所要求的承载能力和延性;加大环梁截面高度与纵梁截面高度的比例,可将试件破坏时混凝土的压碎区由环梁斜裂缝下端转移到纵梁端下部,从而形成纵梁端发生弯曲破坏的理想破坏模式。     

配置HRB600E高强钢筋的混凝土柱抗震性能试验研究

HRB600E钢筋是一种新型高强度钢筋,为改善矩形柱抗震性能并推广HRB600E级高强钢筋的应用,通过对6个配置HRB600E钢筋的不同轴压比、不同钢筋强度和纵筋配筋率的混凝土矩形柱进行低周往复荷载试验,得到试件的滞回曲线、骨架曲线和纵筋应变曲线。对比分析高强钢筋混凝土柱的破坏特征、滞回特性、骨架曲线、刚度退化等抗震性能指标。研究结果表明:配置HRB600E高强钢筋的混凝土柱的破坏特征与配置普通钢筋的混凝土柱相似;通过减小轴压比或增加钢筋强度均能改善配置HRB600E高强钢筋试件的滞回特性、减缓刚度退化、提高试件的抗震性能;配置高强钢筋的构件与高强混凝土配合使用时受力性能更优。     

抗震框架中间层中节点梁筋粘结退化试验研究

根据已经完成的21个接近足尺的钢筋混凝土框架中间层中节点平面梁柱组合体的低周交变加载试验,较全面测试和分析了在轴压比、剪压比、钢筋强度和混凝土强度以及贯穿节点梁筋相对长度的影响下贯穿节点段梁筋的粘结退化规律,通过非线性拟合得到试验加裁制度下贯穿中间层中节点梁筋和混凝土之间粘结应力τ在不同加载阶段的计算公式,提出了受轴压比、剪压比、钢筋强度和混凝土强度等参数影响的贯穿节点梁筋相对长度hc／d的建议公式。     

双向受弯钢筋混凝土简支梁抗剪性能试验研究

根据对正交试验结果和文献试验资料的研究,分析了次生扭矩产生的原因及期 对双向受弯钢筋混凝土简支梁抗剪强度的影响。结合次生扭矩探讨了荷载斜弯角、截面高度比、剪跨比1混凝土强度等级纵筋和箍筋配筋率等因素对有、无腹筋梁抗剪性能的影响。得出了双向受弯你件抗剪强度随着混凝土强度的提高,纵筋和箍筋配筋率的增大而提高,随着剪跨比、荷载斜弯角,截面高度比的增大而降低等结论。     

钢骨高强混凝土梁柱十字节点抗剪性能的研究

就两个不同梁柱刚度比、内置实腹Ｉ字钢的钢骨高强混凝土（＞Ｃ７５）梁柱十字节点试件分别进行了低周反复加载试验,就高强混凝土的作用,型钢腹板、箍筋、翼缘框等对节点的抗剪能力贡献进行了分析,对不同梁柱刚度比的抗剪能力做了对比,并提出了这种结构的节点抗剪承载力公式。     

超高压变电构架钢管混凝土Y型相贯节点平面内受弯性能研究

以国内首例采用钢管混凝土的750kV超高压变电构架工程为背景,设计了3个1:2缩尺、主管灌注混凝土的Y型相贯节点试件,其中包括2个采用不同加强方式(即瓦形板、外套筒加强)和1个作为对比的无加强节点试件,并对其进行了平面内受弯性能试验。试验结果表明：相比无加强节点,采用的2种加强节点的最终破坏形态均为支管失效破坏,均符合“强柱弱梁”的设计原则;节点的转动刚度和受弯承载力均显著提高,平面内转动刚度均可达到欧洲规范规定的刚性节点要求,且平面内受弯承载力基本可以达到支管全截面塑性时的弯矩值。此外,对节点的有限元分析表明：主管轴压比、瓦形板长度和宽度对节点刚度和承载力影响较小,而瓦形板厚度对此影响较为显著。