Analysis Of Force-Finding, Optimization And Construction Simulation For Composite Cable Domes

Cable dome is a kind of flexible tensegrity structure with high efficiency,which has become one of the hot spots of research and application in engineering.The application of rigid roof in cable dome puts forward higher requirements for its grid division.Therefore,this paper proposes a composite cable dome,which can give consideration to both economical efficiency and reasonable span requirements of rigid roof purlin.Taking the structure as the analysis object,the force-finding,prestressing optimization and construction simulation are studied.The main contents are as follows:(1)The structural form of composite cable dome was proposed,and the geometric configuration and force-finding analysis were carried out.The influence of setting the inner ring,the circumferential isodisperse,the number of hoop cables and structural form on the number of self-stress modes and the displacement modes of composite cable dome are discussed.The results show that on the premise of ensuring the outermost mesh size meets the reasonable span of rigid roof purlin,compared with traditional cable dome,composite cable dome has less total number of members and simpler joint structure.Compared with the original shapes,the number of displacement modes can be reduced by using herringbone double struts,not setting the inner ring and reducing the circumferential isodisperse and the number of hoop cables.Therefore,in engineering practice,it is recommended to adopt a smaller circumferential isodisperse and the number of hoop cables,and to adopt the structural form of herringbone double struts if necessary.(2)The advantages and disadvantages of Plant Growth Simulation Algorithm(PGSA)and its improvement strategy are studied.The grading PGSA is proposed to optimize the prestress of composite cable dome,and the results are compared with other algorithms.The results show that after introducing the hybrid improvement strategy of three-stage step,large-scale growth and screening mechanism,the grading PGSA effectively solves the problems in the traditional PGSA,such as weak exploration ability of single step,saturation of two-stage step and large growth space of original three-stage step.Compared with other global optimization algorithms,the grading PGSA runs fewer times,and the initial strain energy of the optimized structure is smaller.When the growth space is limited,it has higher optimization efficiency and better optimization results.(3)The construction simulation analysis is carried out on the traditional construction methods of the composite cable dome structure,such as pretensioning the diagonal cables from outer to inner,only pretensioning the outer diagonal cable,pretensioning the hoop cables from outer to inner,only pretensioning the outer hoop cable,adjusting the length of struts from outer to inner.On this basis,the construction optimization method of alternating lifting the inner ring and tensioning outermost hoop cable is proposed,and the inner ring height of step-by-step lifting is optimized.The results show that in the traditional construction method,the average strain energy in the construction process of pretensioning the hoop cables from outer to inner is the smallest,the proportion of the internal cable force in the construction process exceeding the internal force in the formed state is the smallest by pretensioning the diagonal cables from outer to inner,and the maximum cable force in different construction methods appears in the tension process rather than the formed state.Compared with the traditional construction method,the construction optimization method of alternating lifting the inner ring and tensioning outermost hoop cable solves the problem of large fluctuation of cable force.The cable force in the construction process will not exceed those in the form,and the average structural strain energy is the lowest.In practical engineering,for the construction simulation analysis of similar structures,it is recommended to adopt the construction method of alternating lifting the inner ring and tensioning outermost hoop cable,and determine the inner ring height of step-by-step lifting by optimization.