Research On Mechanical Performance And Morphology Optimization Of New CEG Composite Thin Shell Structure

The traditional concrete thin shell structures were widely applied in the early 20 th century.By the 1950 s and 1960 s,the development of thin shell structure entered a golden age.However,two shortcomings of the thin-shell structure have become increasingly prominent with the construction of large-scale structures.One is that the the construction cost of the thin shell structure is too high.The statistical results show that the construction cost of the thin shell structure is about 60% of the total cost.The other is that when the thin shell structure covers the large space,the vertical stiffness is weak due to the thin thickness,and the stable bearing capacity is low.After the 1970 s,more attractive new lightweight and large-span spatial structures such as mesh structures and tension structures have emerged,and the application of concrete thin shell structures has become less and less.However,thin shell structures are still attracting interest among the architects because of its beautiful shape and reasonable bearing configuration,and many scholars are trying to improve and develop concrete thin shell structures.They are still indispensable form of space structures.Numerous studies have shown that it is meaningful to improve the thin shell structure from both structural shapes and composite materials to meet modern needs and applications.Therefore,in this paper,an innovative CEG(Concrete/EPS-foam/Glass-fiber)composite thin shell is proposed based on the idea of adding new materials.The new CEG composite thin shell adds GFRP(Glass-Fiber Reinforced Plastics)as the bottom face sheet and EPS(Expanded Polystyrene)panel as the core,while retaining the traditional concrete material as the top layer.To investigation the mechanical properties of the innovation CEG composite thin shell,the calculation formula of bearing capacity based on the shallow shell model was established by theoretical analysis.Secondly,the static analysis and nonlinear analysis were carried out by the finite element software ANSYS.Finally,the scale test of the new CEG composite thin shell was carried out and the traditional concrete thin shell specimen also under test as a comparison.Good argument has been observed between the theoretical analysis,numerical results and experimental response;the new CEG composite thin shell bearing capacity is 169% higher than the traditional concrete thin shell.And the ductility is better.Then,using the topology optimization method,the new CEG composite thin shell was optimized from the idea of improved structural form.According to the optimization results,a folded CEG composite thin shell was constructed.The bearing capacity performance and failure mode of the folded CEG composite thin shell was compared and analyzed by the scale model test.The results show that the bearing capacity of the folded CEG composite thin shell can be increased by 81% compared with the CEG composite shell.The typical failure mode is the tensile failure of the top concrete layer at the mid-span position.And the presence of the bottom GFRP face sheet delays the the generation and expansion of cracks in the top concrete layer which indicates a ductile damage.