结构混凝土构件的设计和分析是一个具有实际意义的课题。虽然有时仅根据简单的例子讨论扭转效应，但实践工程师面临着在其各种结构和荷载布置的设计中包括扭转效应的需要。本特别出版物（SP）包含有关钢筋和预应力混凝土构件扭转设计的论文。SP的重点是根据不同的混凝土桥梁和建筑规范的实际设计示例。除了设计实例外，还增加了关于结构混凝土中扭转的最新技术，以及扭转失效的混凝土构件分析和设计的最新进展的论文。本SP的目标是为实践工程师提供必要的工具，以便更好地理解和设计用于扭转的混凝土构件。 在ACI-ASCE联合委员会445“剪切和扭转”和小组委员会445-E“扭转”编制了关于扭转的最新报告后，出现了对本SP的需求。通常，工程教育中对扭转的关注仅限于简化的教科书示例。本SP中的示例展示了扭转设计与弯曲和剪切设计相结合在桥梁和建筑中的应用。此外，本SP中的示例提供了使用不同桥梁和建筑规范时不同结果的见解。最后，包括理论考虑在内的论文使实践工程师对结构混凝土中的扭转有了更深入的理解和背景。本SP中包含了一组国际作者的观点，随后代表了工程师在实践中可能遇到的各种建筑和桥梁规范。 特别是，来自美国、加拿大、厄瓜多尔、荷兰、意大利、希腊和捷克共和国的作者对本SP中的论文做出了贡献。包括学术界和业界的观点。为了交流扭转临界结构的设计经验以及扭转方面的新研究见解，ACI-ASCE联合委员会445和小组委员会445-E在2020年ACI秋季大会上组织了两次会议，题为“受扭转钢筋混凝土和预应力混凝土构件的设计示例”。本SP包含几篇专家的技术论文，这些专家在这些会议上介绍了他们的工作，此外提交的论文仅供发表。总而言之，本SP介绍了桥梁和建筑中受扭构件的大量实例，以及最近研究中应用于受扭构件实际案例的见解。 本SP的联合编辑感谢作者的贡献，并真诚地珍惜他们在准备本卷论文方面投入的时间和精力，以及手稿审稿人的贡献。

The design and analysis of structural concrete elements is a topic of practical interest. While sometimes the effect of torsion is only addressed based on simple examples, practicing engineers are faced with the need to include the effects of torsion in their designs of a variety of structures and load arrangements.This Special Publication (SP) contains papers about the design of reinforced and prestressed concrete elements for torsion. The focus of the SP is on practical design examples according to different concrete bridge and building codes. In addition to the design examples, papers dealing with the current state of the art on torsion in structural concrete, as well as recent advances in the analysis and design of concrete elements failing in torsion, are added.The objectives of this SP are to provide practicing engineers with the tools necessary to better understand and design concrete elements for torsion. The need for this SP arose after the development of the State-of-the-Art Report on Torsion of Joint ACI-ASCE Committee 445 "Shear and Torsion" and Subcommittee 445-E "Torsion". Usually, the attention that is paid to torsion in engineering education is limited to simplified textbook examples. The examples in this SP show applications in bridges and buildings, where the torsion design is combined with the design for flexure and shear. Additionally, the examples in this SP give insight on the different outcomes when using different bridge and building codes. Finally, the papers that include theoretical considerations give practicing engineers a deeper understanding and background on torsion in structural concrete.The views from an international group of authors are included in this SP, subsequently representing a variety of building and bridge codes the engineer may encounter in practice. In particular, authors from the United States, Canada, Ecuador, the Netherlands, Italy, Greece, and the Czech Republic contributed to the papers in this SP. Views from academia and the industry are included.To exchange experience in the design of torsion-critical structures as well as new research insights on torsion, Joint ACI-ASCE Committee 445 and Subcommittee 445-E organized two sessions titled "Examples for the Design of Reinforced and Prestressed Concrete Members under Torsion" at the ACI Fall Convention 2020. This SP contains several technical papers from experts who presented their work at these sessions, in addition to papers submitted for publication only.In summary, this SP addresses numerous practical examples of structural elements under torsion in bridges and buildings, as well as insights from recent research applied to practical cases of elements under torsion. The co-editors of this SP are grateful for the contributions of the authors and sincerely value the time and effort they invested in preparing the papers in this volume, as well as the contributions of the reviewers of the manuscripts.