Behaviour of Reinforced Concrete Conical Tanks under Hydrostatic Loading

Reinforced concrete conical tanks are used in municipalities and industrial applications as liquid containing vessels. Such tanks can be ground supported tanks or elevated on a supporting shaft. Although most design codes provide guidelines for rectangular and cylindrical tanks, no guidance is provided in such codes for conical tanks. Therefore, this thesis is motivated to study the behaviour and design of this type of tanks. In the current study, the accuracy of a design approach based on the provisions of Portland Cement Association (PCA-CCTWP) code for cylindrical tanks combined with an equivalent cylindrical approach provided by the American Water Works Association AWWA-D100 (2005) is assessed. This assessment is done by comparing the internal forces resulting from this method with those obtained from a linear finite element analysis model built in-house. It is noticed that in some of the studied tanks, the PCA-CCTWP approach combined with the equivalent cylinder method is found to be unsafe. As such, and due to the complexity of analysing these conical tanks, a simplified design approach in the form of design charts is provided in this study. This set of charts can be easily used for the analysis and design of reinforced concrete conical tanks subjected to hydrostatic pressure and having a constant wall thickness. This approach is developed using the results obtained from finite element analysis of a wide range of reinforced concrete conical tanks having different configurations combined with code requirements. This simplified approach is then utilized to investigate the economics of reinforced concrete conical tanks versus steel counterparts. A cost analysis is conducted for several conical tanks having different capacities and different construction materials by including both construction and life-cycle costs. In addition to the cost analysis, a general study of the effect of tank dimensions on its cost is illustrated

STR-860: COST ANALYSIS OF CONICAL TANKS; COMPARISON BETWEEN REINFORCED CONCRETE AND STEEL

This paper provides a cost analysis case study to compare the effectiveness of using reinforced concrete versus steel as a construction material for conical tanks. Simplified design approaches, which were developed in previous investigations, are utilized to design a wide range of reinforced concrete conical tanks and steel counterparts having three different capacities (500 m3, 1750 m3 and 3000 m3). The cost analysis is conducted for each of the concrete and steel tanks. This analysis includes the cost of material, formwork, labour and life-cycle cost. Also, a general study of the effect of tank dimensions on the cost is provided. The results of this study show that steel conical tanks are considered as a more economical choice for medium and small capacity tanks, regardless their dimensions. On the other hand, for large capacity conical tanks (3000 m3), the tank dimensions govern which construction material (reinforced concrete or steel) is more cost effective

MAT-716: GREEN SIDEWALKS USING SUSTAINABLE TWO-STAGE CONCRETE

Two-stage concrete (TSC) is a special type of concrete, which has a high potential for use in sidewalk construction owing to its high volume stability. TSC is characterized by its high coarse aggregate content. Hence, using recycled solid waste materials as a coarse aggregate will increase TSC sustainability, while providing a cost-effective alternative to natural aggregates. Aggregates are pre-placed in TSC. Hence, water absorption by recycled concrete aggregates and the associated rheology problems do not exist in TSC. This study explores the performance of green TSC sidewalks incorporating recycled concrete aggregates (RCA) and crumb rubber from scrap tires. Mechanical properties of the proposed green TSC including compressive strength, modulus of elasticity, flexural strength and toughness, as well as durability to freeze-thaw cycles were investigated. Results show a slight reduction in TSC mechanical properties due to the use of RCA. Moreover, incorporating tire particles reduced TSC mechanical properties significantly, while improving its toughness and freeze-thaw resistance. Addition of recycled tire steel wires allowed to overcome the negative effects on the mechanical properties induced by crumb tire rubber. Therefore, recycling solid waste materials in TSC sidewalks can be an effective strategy to beneficiate such waste materials