Innovative detailing for shear in concrete using high performance materials

现有的钢筋混凝土剪切设计模型使用基于应力的构件强度组合方法，从混凝土贡献和基于桁架类比的剪切钢筋贡献来计算构件强度。这些模型限制了设计中允许的抗剪钢筋的最大强度，以便限制失效时的裂缝宽度。剪力筋的最大间距由经验规则根据内部桁架的假设角度来确定。自20世纪60年代以来，有限的研究表明，当这些标准中的任何一个放松时，安全设计是可能的。改进的剪切能力模型，直接考虑剪切钢筋应变和间距，将允许经济和安全的使用现代，耐用的钢筋材料作为箍筋。本研究将通过实验室和数值研究探讨抗剪钢筋纵向间距对抗剪能力的影响。将考虑具有新建筑代表性的剪切钢筋布置，以及适合修复应用的剪切销钉配置。还将考虑由于使用高强度钢或纤维增强聚合物材料而导致的较高箍筋应变在破坏时的影响。在实验调查中，将特别强调现有测试数据很少的配置，包括具有宽加固间距的大型构件。非线性数值模型，新的测试数据，以及对现有设计方法的严格检查，将允许开发一种新的基于应变的剪切设计方法，该方法可以考虑箍筋间距，结合箍筋的机械性能。这个模型将允许更多的创新细节发生在实践中，为成员稀疏间隔高性能增强材料。此外，预测现有成员能力的能力将得到改善，从而最大限度地减少不必要和昂贵的康复。

Existing shear design models for reinforced concrete use a stress-based compositional approach to member strength, from both a concrete contribution and from a shear reinforcement contribution based on a truss analogy.  These models limit the maximum strength of the shear reinforcement permitted in design, in order to limit crack widths at failure.  Maximum spacing of the shear reinforcement is defined by empirical rules based on an assumed angle for the internal truss.  Limited studies since the 1960's have shown that safe designs are possible when either of these criteria are relaxed.  Improved capacity models for shear that directly consider both the shear reinforcement strains and spacing, will permit economical and safe use of modern, durable reinforcement materials as stirrups.     This study will investigate influences on shear capacity from the longitudinal spacing of shear reinforcement, through laboratory and numerical studies.  Shear reinforcement arrangements representative of new construction will be considered, along with shear dowel configurations suitable for rehabilitation applications.  The influence of higher stirrup strains at failure, resulting from the use of high strength steel or fibre reinforced polymer materials, will also be considered.  A special emphasis in experimental investigations will be placed on configurations where little existing test data is available, including large members with wide reinforcement spacing.     Non-linear numerical models, the new test data, and a critical examination of existing design methods will permit development of a new strain-based shear design approach which can account for stirrup spacing, in combination with the stirrup mechanical properties.  This model will permit more innovative detailing to occur in practice, for members with sparsely spaced high performance reinforcing materials.  Furthermore, the ability to predict the capacity of existing members will be improved, thereby minimizing unnecessary and costly rehabilitation.