Towards a Rational Design Procedure for Concrete Liquid Containing Structures

含液结构（LCS）作为环境工程设施的一部分，主要用于水和污水处理厂以及其他工业废物。在加拿大，它们通常由矩形或圆形结构的钢筋混凝土建造。这些结构被认为是生命线设施，需要仔细设计和细节，以满足裂缝和泄漏控制的可用性要求。目前在北美很少有关于LCS设计的指导方针和标准。就在最近，加拿大标准协会（CSA）制定了污水处理厂设计标准，该标准将很快发布。美国混凝土协会（ACI Committee 350）已经制定了混凝土LCS的规范和注释。对于这类重要的结构，不同的设计准则和标准之间存在很大的不一致性。这主要是由于对这些结构的抗震性能缺乏了解。近年来，申请人对混凝土LCS的行为进行了广泛的分析研究。结果表明，现行的设计规范和标准不能代表这类结构的实际性能。主要关注的问题是受弯曲和/或直接拉伸的构件的裂缝宽度和泄漏之间的关系，温度和收缩的影响，由于混凝土板和墙的裂缝限制以及与地震荷载有关的问题。一个重要的问题与用于确定地震等效基底剪切的响应修正系数R有关。因此，计划对墙-板连接进行全尺寸试验。在墙-基础连接处安装钢制水压室，模拟液-罐相互作用，检测罐壁关键区域内可能发生的泄漏。基于上述讨论，本研究的主要目标是通过分析和实验程序，为钢筋混凝土储罐制定合理的设计程序，以确保安全的防泄漏结构。在试验方案中，试件在静、动两种载荷下同时进行液体压力和泄漏试验。根据这项研究的结果，将使用基于可服务性要求和保护水平的性能标准来确定R值。该项目还包括基于非线性有限元方法的分析研究。此外，本研究还将采用有限元方法对混凝土高架水箱的抗震性能进行分析研究。它旨在为代码决策提供必要的输入。

Liquid containing structures (LCS) as part of environmental engineering facilities are primarily used for water and sewage treatment plants and other industrial wastes. In Canada, they are normally constructed of reinforced concrete in the form of rectangular or circular configurations. These structures are considered as lifeline facilities that require careful design and detailing to meet serviceability requirements for crack and leakage control. There are currently few guidelines and standards available in North America for the design of LCS. Only recently, the Canadian Standards Association (CSA) has developed a Standards for the design of Wastewater Treatment Plants which is due to be published very soon. The American Concrete Institute (ACI Committee 350) has developed a code and commentary for concrete LCS. There is a great deal of inconsistency among different design guidelines and standards for this important broad class of structures. This is mainly due to the lack of understanding of the seismic behavior of these structures. In recent years, the applicant has carried out extensive analytical investigations on the behavior of concrete LCS. The results have indicated that the current design codes and standards do not represent the actual behavior of these types of structures. The main issues of concern are the relationship between the crack width and leakage for members subjected to flexure and/or direct tension, effects of temperature and shrinkage due to restraints on cracking in concrete slabs and walls as well as those issues related to seismic loading. One important issue is related to the response modification factor, R, used for determining the equivalent base shear because of earthquakes. As a result, full scale experiments are planned to be performed on wall-slab connections. A steel water pressure chamber will be installed at the connection of the wall-foundation to simulate the liquid-tank interaction and to enable the detection of possible leakage within the critical regions of the tank wall. Based on the above discussion, the main objectives of the proposed research study is to develop a rational design procedure, through analytical and experimental programs, for reinforced concrete tanks that assures a safe leak resistant structure. In the experimental program, specimens while under loads which include hydrostatic, and dynamic will be simultaneously subjected to liquid pressure and leakage tests. Based on the results of this study, a performance criterion based on serviceability requirements and the level of protection will be used to establish the R values. This project also includes analytical studies which will be based on non-linear finite element method. Also, analytical investigations on the seismic behavior of concrete elevated water tanks using the finite element method will be performed in this study. It is intended to provide the necessary input for code decision making.