Seismic and Service Life Assessment of Reinforced Concrete Structures and Novel Cementitious Materials Application for Durable and Resilient Construction

该提案解决了地震和使用寿命评估以及现有钢筋混凝土结构改造方面的开放性问题。总体框架是基于性能的，因此验收标准以单个构件和完整结构系统的变形能力估计（DC）来表示。虽然已建立的规范提供了估计直流的方法，但与实验证据的比较表明，对该参数的理解非常差，对实际值的不确定度高得令人无法接受。因此，本研究的主要目的是提高对钢筋混凝土DC下力学的理解，并将基于性能的评估方法扩展到腐蚀结构。在此背景下，该项目还将开发受腐蚀影响的结构的使用寿命估计和性能标准的方法。在整合相关数据库后，将对现有的实验证据进行集体审查，并在实验室进行额外的测试，并通过先进的非线性有限元研究，以阐明重要参数（如屈服渗透、塑性铰定义、轴向载荷效应和破坏模式层次）对DC的物理意义。这将扩展到包括腐蚀渗透深度，钢面积损失和覆盖的脆化，腐蚀影响成员的直流。特别强调的是改进粘结的表现和钢筋屈服对应变发展能力的影响；将进行相关实验，研究其对直流的影响，包括实验室模拟腐蚀后锚固/搭接部分腐蚀的情况。应用改进的DC估计的案例研究，特别是当考虑到构件剪切跨度中屈服扩散的重要影响时，将作为基于性能的设计和评估的范例。

The proposal addresses open issues in seismic and service life assessment and retrofit of existing reinforced concrete construction. The general framework is performance based, whereby the acceptance criteria are expressed in terms of Deformation Capacity estimates (DC) for the individual members and complete structural systems. Although the established Codes provide methods for estimation of DC, comparison with experimental evidence illustrate that this parameter is very poorly understood with unacceptably high margin of uncertainty to real values. For this reason the main objective of the study is to develop improved understanding of the mechanics that underly the DC of reinforced concrete, and to extend the performance based methods of assessment to corroded structures. In this context the project will also develop methods for service life estimation and performance criteria for corrosion affected structures. The available experimental evidence will be reviewed collectively after assembly of relevant databases, and additional tests will be undertaken in the lab and through advanced nonlinear finite element studies in order to clarify the physical significance of important parameters such as yield penetration, plastic hinge definition, axial load effects, and hierarchy of failure modes, on DC. This will be extended to include depth of corrosion penetration, steel area loss and embrittlement of the cover, for DC of corrosion affected members. Particular emphasis will be placed in improved representation of bond and the effects of bar yielding on strain development capacity of reinforcement; relevant experiments will be conducted to study its effect on DC, including the case of partially corroded anchorages/lap splices after simulated corrosion in the lab. Case studies of application of the improved estimates of DC, particularly when accounting for the important effects of yield spreading in the shear span of members, will be developed as model examples of performance based design and assessment. The structural performance of strain-hardening cementitious composites (SHCC) will be studied experimentally to resolve open issues in design of new structures (aiming for simpler construction through minimization of required stirrup reinforcement), and to implement them in innovative repair solutions of the systemic problems encountered in old structures. Functionalization of SHCC by engineering the nanostructure (through nano-additives) and combining different types of synthetic fibres and fibre coatings will be pursued for the various intended applications. Tests will explore the structural behavior of structural members constructed with SHCC so as to provide a basis for development of design rules to support their introduction in new construction but also in retrofitting methods, by taking advantage of the internal confinement afforded by SHCC due to their fiber content.