| Earthquake is one of the most serious natural disasters faced by human being. China is an earthquake-prone country with great losses caused by earthquakes, so it is quite necessary and urgent to study the seismic performance of structures and bridge. Seismic force is related to the weight of structure, which can be decreased by reducing the building dead-load. Lightweight aggregate concrete (LAC) has great potential applications in seismic structure for its advantages of low density, high specific strength, crack resistance, earthquake-proof, and high cooperation deformation capability with reinforcement during elastic stage. However, LAC can't be used directly into reinforced concrete column due to its disadvantages of low compressive strength, low modulus and high brittleness. In this thesis, based on the research of interface strengthening technology, the high strength lightweight concrete (HSLC) was prepared, and which was confined by multi-spiral stirrups. The multi-spiral confined HSLC column has good ductility and seismic performance. The multi-spiral stirrups with less steel consumption greatly reduce the cost of earthquake resistance protection of compression member.The main results obtained in this study are as follows:Main factors influencing the mechanic properties of HSLC were found out. Key technique of interface strengthening for preparing HSLC was grasped. The proportion parameters of HSLC, high strength concrete (HSC) and high strength. lightweight concrete (HSLAC) with the same strength of C60 were confirmed. The stress-strain curves of HSLC, HSC and HSLAC were obtained by tests; the deformation properties, failure model and damage mechanism were also discussed. Formula of constitutive relations model of HSLC was revised, which established the theoretic foundation for structural design and finite element analysis.In order to study the match relationship between concrete and stirrups, failure patterns, "P-â–³" hysteretic curves, skeleton curves, ductile coefficients, energy dissipation and strength degeneration of steel reinforced HSLC, HSC and HSLAC columns were studied by low cyclic reversed loading test. Results indicate that HSLC can reduce the weight of structures, so as to decrease the earthquake destructive force; it can also meet the need of important building on load capacity, ductility and stiffness.The toughening seismic design idea of multi-spiral stirrups for confined HSLC was proposed, and 8 multi-spiral confined HSLC column specimens were prepared for the low cyclic reversed loading test. Based on the three-direction stress law of confined concrete, the load carrying capacity of the rectangular cross section concrete column with multi-spiral is analyzed, and the calculated equation of the load carrying capacity is proposed, which provides a theory and calculation basis for multi-spiral confined concrete column design and research.The seismic performances of single spiral,4-spiral and 5-spiral HSLC columns were studied, including failure patterns, hysteretic curves, skeleton curves, ductile coefficients, energy dissipation and strength degeneration. The influences of axial compression ratio and reinforcement ratio on the seismic properties of 5-spiral confined HSLC columns were discussed. It is verified through experiments that multi-spiral confined concrete columns have better mechanical properties than single spiral columns and the multi-spiral significantly increase the column's strength, plasticity, ductility and anti-seismic capability. Under the same seismic fortification level, the multi-spiral stirrup reduces the steel consumption by more than 15%.
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