In many industrialized countries, structural assessment of existing structures and infrastructure is becoming a crucial issue. Since many of them have already reached their design service life, assessing their actual condition in order to evaluate their remaining service life is, today, of fundamental importance.

Depending on the environmental conditions, carbonation‐induced corrosion, chloride‐induced corrosion, or corrosion‐induced by chloride additives into concrete are among the main causes of the degradation of reinforced concrete (RC) and prestressed concrete (PC) structures.

Since environmental attacks due to chloride contents or carbonatation are increasing in time, the capacity of corroded existing members is gradually being reduced, thus causing unexpected failures due to a capacity failure in bending or shear or anchorage resistance. The lack of robustness of supporting structural frames, sometimes due to the adoption of isostatic structural schemes, is very often the cause of progressive collapses of reinforced concrete structures.

Therefore, corrosion can reduce the structural performances not only in the case of persistent or transient design situations but also in the case of accidental situations or seismic situations.

Moreover, corrosion can have detrimental effects on durability.

Despite all this, very little data are available on the reliability of numerical and design approaches for predicting the structural behavior of buildings and infrastructure affected by damage, induced by corrosion processes.

The corrosion of existing structures is a topic that has recently elicited a lot of interest. This intensified level of attention has augmented over time due to the regular occurrence of structural failures triggered partially or entirely by material deterioration.

Citation databases that analyze documents on an annual basis have registered fewer than 30 scientific documents on corroded reinforced concrete structures published before 2002 in the entire world. Since 2002, the number of documents addressing corrosion of reinforced concrete and being available for the scientific community has seen a consistent rise, reaching a maximum in 2018.

A Study Day on this topic was organized in Parma—Italy—on March 25, 2019, known as INTERNATIONAL CACRCS DAY, where CACRCS stands for “Capacity Assessment of Corroded Reinforced Concrete Structures.” The event, supported by fib and CTE (where CTE stands for Collegio dei Tecnici dell'Industrializzazione Edilizia), aimed at bringing together professionals from the concrete industry as well as academics from all over the world. It offered an excellent forum for engineers, scientists, concrete technologists, researchers, academics, and practitioners to exchange knowledge about advances in the field of corrosion of reinforced concrete structures.

This issue is a collection of a part of the papers presented during CACRCS DAY because some of these papers have already been published in previous issues of Structural Concrete. A virtual issue (online) will shortly be available with all the papers presented during CACRCS DAY and accepted for publication.

It is well known that during the phases of inspection, structural assessment, condition assessment, decision‐making and interventions regarding existing reinforced concrete structures, various essential skills are involved. Consequently, the assessment of the capacity of corroded reinforced concrete structures involves several disciplines in which the fundamentals of material science and technology and structural engineering play a major role.

This issue exemplifies this multidisciplinary approach required for the capacity assessment of corroded concrete structures by presenting both papers related to corrosion processes and material damage detection as well as papers related to the structural response of members through the adoption of experimental and numerical approaches.

In order to better understand the corrosion processes, this issue contains new findings on the mechanisms involved in the initial steps of corrosion and in the assessment of the propagation period.

The failure mechanisms of corroded members can be very different from the ones of non‐deteriorated members. This issue presents additional contributions dedicated to experimental tests on corroded members that explore the effects of corrosion at the structural scale.

In order to assess the response prediction capability of numerical and design tools, there is a strong need for benchmarks. Due to this necessity, some papers presented in this issue focus on the comparison between the capacity of reinforced and prestressed concrete members, experimentally and numerically obtained.

To this end, the issue presents a proposal for an extension of fib Model Code 2010 formulations for the analytical prediction of the capacity of corroded reinforced concrete beams.

Due to the fact that the buckling of longitudinal reinforcement in columns or bridge piers—subjected to cyclic loading—is a mechanism triggered by corrosion processes, being able to predict it is of paramount importance for the evaluation of the structural safety of existing structures located in seismic areas. Regarding this specific subject, the issue contains some papers presenting numerical methods and analyses allowing to evaluate the degrading seismic capacity of reinforced concrete members often affected by the instability of longitudinal reinforcement.

In the framework of Level of approximation IV and according to Model Code 2010, a submission is dedicated to the description of a non‐linear finite element method for the response prediction of PC beams without transversal reinforcement.

Finally, the issue presents a piece on the assessment of the residual service life of reinforced concrete structures and some protection strategies, such as cementitious coatings or green inhibitors.

I hope you that you will enjoy reading this issue and that the presented papers will inspire young researchers in pursuing their studies, will help colleagues in starting or continuing fruitful cooperative efforts and will aid practitioners in finding solutions to daily issues. The preservation of the structural heritage requires that all these types of expertise remain securely available for our society.

在许多工业化国家，对现有结构和基础设施进行结构评估已成为至关重要的问题。由于它们中的许多已经达到其设计使用寿命，因此今天评估其实际状况以评估其剩余使用寿命至关重要。

根据环境条件，碳化引起的腐蚀，氯化物引起的腐蚀或氯化物添加剂腐蚀混凝土引起的腐蚀是导致钢筋混凝土（RC）和预应力混凝土（PC）结构退化的主要原因。

由于由氯化物含量或碳酸化引起的对环境的侵害随着时间的增加而增加，已腐蚀的现有构件的能力逐渐降低，从而由于抗弯强度或抗剪能力或抗锚固能力的下降而引起意想不到的破坏。有时由于采用等静压结构方案而导致支撑结构框架缺乏坚固性，通常是钢筋混凝土结构逐渐倒塌的原因。

因此，腐蚀不仅会在持续或短暂的设计情况下，而且在意外情况或地震情况下，都会降低结构性能。

此外，腐蚀会对耐久性产生不利影响。

尽管如此，关于预测腐蚀过程导致的建筑物和基础设施的结构行为的数值和设计方法的可靠性的数据很少。

现有结构的腐蚀是最近引起人们极大兴趣的话题。随着时间的流逝，由于部分或全部由材料劣化引起的结构性故障的经常发生，人们的注意力日益增强。

每年对文献进行分析的引文数据库在全世界注册的腐蚀钢筋混凝土结构的科学文献不到30篇。自2002年以来，有关钢筋混凝土腐蚀并可供科学界使用的文件数量一直在不断增加，到2018年达到最大值。

关于这一主题的研究日于2019年3月25日在意大利帕尔马举行，被称为国际CACRCS日，CACRCS代表“腐蚀钢筋混凝土结构的承载力评估”。这项活动由fib和CTE（CTE代表Collegio dei Tecnici dell'Industrializzazione Edilizia）支持，旨在汇聚来自混凝土行业的专业人员以及来自世界各地的学者。它为工程师，科学家，混凝土技术人员，研究人员，学者和从业人员提供了一个很好的论坛，以交流有关钢筋混凝土结构腐蚀领域的进展的知识。

本期是在CACRCS DAY期间提交的部分论文的集合，因为其中一些论文已在以前的结构混凝土杂志上发表。虚拟事件（在线）将在CACRCS DAY期间提供，并被收录出版。

众所周知，在有关现有钢筋混凝土结构的检查，结构评估，状况评估，决策和干预阶段，涉及各种基本技能。因此，对钢筋混凝土结构腐蚀能力的评估涉及多个学科，其中材料科学，技术和结构工程的基本原理起着重要作用。

该问题通过介绍与腐蚀过程和材料损伤检测有关的论文，以及与采用试验和数值方法有关构件的结构响应有关的论文，举例说明了腐蚀混凝土结构能力评估所需的这种多学科方法。

为了更好地理解腐蚀过程，此问题包含有关腐蚀初始步骤和传播时间评估的机理的新发现。

受腐蚀的构件的破坏机制与未退化的构件的破坏机制可能非常不同。本期杂志提供了专门用于腐蚀构件的实验测试的其他贡献，这些构件在结构规模上探索了腐蚀的影响。

为了评估数值和设计工具的响应预测能力，强烈需要基准测试。由于这种必要性，本期发表的一些论文着重于通过实验和数值方法对钢筋混凝土和预应力混凝土构件的承载能力进行比较。

为此，该问题提出了关于扩展fib Model Code 2010公式的建议，以用于对腐蚀的钢筋混凝土梁的承载能力进行分析预测。

由于柱或桥墩中的纵向钢筋屈曲（受循环荷载作用）是腐蚀过程触发的一种机制，因此能够对其进行预测对于评估位于该处的现有结构的结构安全性至关重要。地震区。关于该特定主题，该问题包含一些提出数值方法和分析的论文，这些论文可以评估经常受纵向钢筋不稳定性影响的钢筋混凝土构件的抗震性能。

在近似IV级的框架内，根据Model Code 2010，提交的文件专门用于描述无横向加固的PC梁响应预测的非线性有限元方法。

最后，本期文章对钢筋混凝土结构的剩余使用寿命进行了评估，并提出了一些保护策略，例如水泥涂料或绿色抑制剂。

希望您喜欢阅读本期杂志，并且所发表的论文将启发年轻的研究人员继续他们的研究，将帮助同事们开始或继续进行卓有成效的合作努力，并帮助从业者找到解决日常问题的方法。结构遗产的保存要求所有这些类型的专业知识都必须对我们的社会安全地可用。