Self-healing, Leakage Experimental Investigations And Seismic Response Analyses Of The Ground Reinforced Concrete Tank

Reinforced concrete water tanks which play important functions in the whole water supply system for water purification and storage are typical liquid containing structures. The cracks occurrences of water tanks accelerate steel corrosion and reduce structure durability. The limit of crack width for structure design largely determines reinforcement quantity. Cracks are prone to occur when tanks surfer from earthquakes and may lead to liquid leakage, which make functionality of liquid containing structures decline or even lost and somewhat affect the function of whole water supply system. The cracking behaviors as well as liquid leakage are the main standards to judge earthquake damage level of tanks after a quake. The current research results show that concrete crack contacted with water have self-healing capability and original crack widths reduce gradually. The water stored in tanks provides necessary conditions for crack self-healing. Therefore, the reasonable crack limits of structure design and earthquake damage classification for water tanks should be comprehensively given base on bearing capacity, durability, serviceability, economy crack self-healing and maintenance availability.The dynamic characteristics of liquid containing structures are changed due to stored liquid. The liquid-structure coupling effect and liquid sloshing exists in liquid containing structures under seismic actions. The vertical direction of the bottom and side of tank bodies bear hydrodynamic pressure generated by liquid except the inertia force and hydrostatic pressure. The liquid sloshing and hydrodynamic pressure should be considered in the seismic design of tanks. At present, the researches about concrete crack self-healing performance, liquid leakage property, dynamic characteristics and tanks seismic response considering liquid-structure coupling effect under seismic actions are incomplete. In this dissertation, self-healing performance and liquid leaking property of concrete cracks are researched by experimental investigations of flexural cracks and penetrating cracks, and dynamic characteristics, liquid sloshing, hydrodynamic pressure as well as damage characteristics are researched by seismic response analyses using ADN1A software.1. The self-healing and leakage experimental investigations for flexural cracking and penetrating cracking of reinforced concrete tank walls are designed and completed. The material performances are test. The self-healing width of flexural microcracks in standing water environment are proposed and self-healing performance of penetrating cracks in moving water environment are analyze based on self-healing experiment results. The influence caused by bending crack width, compressive zone height and water head to liquid leakage property are researched as well as the relationship between leakage rate and cumulative time or water head are analyzed according to leakage experiment results. The experiment results about the relationship between crack characteristics and self-healing or liquid leakage can provide references for earthquake damage classification and structure design of tanks.2. The rigid modal, fluid sloshing modal and liquid-structure coupling vibration modal are obtained by dynamic characteristic analysis of circular tanks. The factors such as water height, tank radius and surface gravity waves affect dynamic characteristics of liquid-structure coupling system are worked out. In addition, the theory and finite element calculation results of sloshing frequency for circular tank are compared, the validity of models are verified. The sloshing foundation period formula of circular reinforced concrete tank is derived since the sloshing foundation period is one of the important parameters for horizontal seismic action calculation.3. The largest wave height of liquid sloshing under unidirectional horizontal earthquake for circular tanks with different tank radiuses and water heights are analyzed and the calculation formula of the largest wave height for circular tank is fitted. The formula can be used for estimating the largest sloshing wave height under unidirectional horizontal earthquake and designing wave height of liquid containing structures. Combine the seismic design response spectra of long period for liquid containing structures and correction coefficient of damping ratio, the calculation method of the largest sloshing wave height for water tank is developed. The largest wave height of liquid sloshing can be used to calculate convective pressure.4. The value and distribution of hydrodynamic pressure on bottom and side bodies for circular tanks with different tank radiuses and water heights under unidirectional horizontal earthquake are analyzed, meanwhile the results are compared with the theoretical results. The seismic peak acceleration, water height and tank radius impacted on hydrodynamic pressure are studied. The superposition method for convective pressure and impulsive pressures is determined. The formulas for convective pressures, impulsive pressures as well as hydrodynamic pressure are fitted. Since theoretical calculation is more complex and standard method just considers impulsive pressures only, combining with the hydrodynamic pressure distribution of bottom radius, hydrodynamic pressure standard values are synthetically confirmed, which are simpler and tally with actual situation than theoretical method or standard method. Furthermore, pressure time history trend at surface and bottom positions of wall are analyzed.5. The dynamic responses of circular tank under bidirectional ground motions are fulfilled and the results of the largest wave height and hydrodynamic pressure are extracted. The largest wave height formula and hydrodynamic pressure formula of circular tank under bidirectional horizontal ground motion are obtained by reasonable combination method based on the responses under unidirectional ground motion. The calculation methods of the largest wave height and hydrodynamic pressure for circular tank under bidirectional horizontal ground motion are presented. And the damage characteristics and seismic vulnerability of circular tanks under bidirectional ground motion are analyzed.