Mechanical Behavior of Single-Layer Two-Way Grid Cylindrical Latticed Shell with Out-of-Plane Tension Members
Single layer two-way grid shell with in-plane and out-of-plane tension members is a new type of single-layer latticed shell roof. This study treats the effects of tension member installation on the buckling load and strength of a single layer two-way grid cylindrical shell roof by the numerical method. The tension members are installed to stiffen the rigidity of a single layer two-way grid shell roof and improve its stability behavior. Tension member installation and placement pattern is focused as both diagonal members of two-way grids and out-of-plane stiffened members in a cylindrical surface. The diagonal member and the out-of-plane member are used to increase the in-plane and the out-of- plane rigidity of a single layer two-way grid shell, respectively. The tension member placement pattern, the load distribution patterns, the initial imperfections and the initial axial force are considered for the numerical calculation parameters. It is confirmed by the numerical analysis that the tension members in out-of-plane and diagonals caused the increase in the buckling and strength of two-way grid shell.
BUCKLING STRENGTH OF TWO-WAY SINGLE-LAYER LATTICE DOMES STIFFENED BY DIAGONAL BRACES
The present paper proposes an effective method to evaluate elasto-plastic buckling loads of two-way single-layer lattice domes, stiffened by diagonal braces, under vertical uniform and non-uniform loads. The domes are shallow and composed of grid chord members, connected rigidly at nodes, and supported by pins at four sides of rectangular plan. First, a formula for linear buckling load is derived based on equivalent shell analogy, followed by a study for a knockdown factor of elastic buckling loads considering geometrical initial imperfections of a magnitude up to L0/1000 for a span L0.The value of 0.65 or a lesser value for a knockdown factor is recommended for use to evaluate elastic buckling loads. Second, column strength curves are discussed and proposed for elasto-plastic buckling loads, and finally, the proposed strength curves are proven effective for evaluating the strength.
Numerical Simulation for Natural State of Two-Phase Liquid Dominated Geothermal Reservoir with Steam Cap Underlying Brine Reservoir
Hydrothermal reservoir which liquid-dominated hydrothermal reservoir is a type of geothermal reservoir that most widely used for power plant. The exploitation of mass and heat from the geothermal fluid will decrease the pressure in the reservoir over time. Therefore the pressure drop in the reservoir will have an impact on the formation of boiling zones or boiling will increase. The impacts are an increase in the fraction of steam, dryness, in the reservoir and with good vertical permeability will form a steam cap underlying the brine reservoir. The two- phase liquid dominated reservoir is sensitive to the porosity and difficult to assign average properties of the entire reservoir when there is boiling zone in some area of the reservoir. These paper showed successful development of two-phase liquid dominated geothermal reservoir and discussed the formation of steam cap above brine reservoir through numerical simulation for state natural conditions. The natural state modeling in steam cap shows a match with the conceptual model of the vapor-dominated developed. These paper also proofed the presence of transition zone, boiling zone, between steam cap and brine reservoir.