Research And Development Of A New Bearing Structure Of The Net Shell Roof On The Large Storage Tank

With the development of large storage tanks in the world and the construction of National Strategic Oil Reserve Bases, the plate-rib fixed roofs on the product oil tanks have shown some shortcomings. So in the storage and transportation system of the petrochemical industry, all kinds of steel and aluminum net shell roofs have been applied to more and more product oil tanks.Although the steel/aluminum net shell roof structures have mature theories and design experience in the construction of modern stadium roof, there are still many problems of how to apply this technology to the large storage tank to study, taking how to connect the net shell roof with the tank wall for example. This subject is derived from the scientific research and technical development project "research and development of the net shell roof structures on the large storage tanks" of China Petroleum Engineering and Construction Corporation (CPECC). The main task is to develop a kind of bearing structure connecting the net shell roof with the tank wall of the large storage tank, making the net shell roof to be better applied to the tank. The main work accomplished and results obtained are listed below:(1) A new bearing structure applied to the large storage tank to connect the net shell roof with the tank wall was proposed independently. The specific structure, working principle, characteristics and material selection suggestions were introduced in detail. Then according to the tank size and design parameters provided by the user, the structure size of the net shell roof and the calculation condition were determined.(2) Finite element analysis of the net shell roof structure’s overall model was carried out. The independent model of the net shell roof and the complete model of the net shell roof combined with the tank were established, and the different bearing structures’effects on the performance of the net shell roof were analyzed. The results showed that new bearing structure was the most beneficial to the net shell roof, making its comprehensive performance best.(3) A simplified analysis model of the net shell roof was proposed. By comparing the analysis results of the independent model and the complete model, it was known that the synergy of tank shouldn’t be ignored when the net shell roof’s mechanical performance was analyzed. With the purpose of not only considering the effects of the tank, but also simplifying the modeling process and facilitating the project promotion, a simplified analysis model of the net shell roof considering the radical stiffness of the tank wall was proposed. And its feasibility was verified preliminarily.(4) The submodel method was adopted to carry out the numerical simulation analysis for the bearing structure. The submodel of the new bearing structure was established. The axial fore and bending moments of the bearing rod were extracted from the analysis results of the net shell roof structure’s overall model and applied to the submodel. Then the finite element analysis was carried out. Meanwhile, based on the primary size of the new bearing structure, the optimization module Design Explorer was adopted to optimize the structure. Eventually, the optimal size of the bearing was determined by adjusting the four parameters D, d, t1, t2.