Refined Analysis On Dynamic Performance And Damage Assessment Of Single-layer Spherical Reticulated Dome Under Strong Earthquake

The single-layer spherical reticulated dome is a kind of structures with mechanical properties of bar structure and thin dome structure,which is widely used in sports stadiums and exhibition centers.The existing earthquake hazard shows that members of the dome may occur damage,buckle and fracture to reduce the bearing capacity,becoming threat to people’s lives and property security.In order to refined analysis on dynamic performance and damage assessment of single-layer spherical reticulated dome under strong earthquake,the dissertation focuses on single-layer spherical reticulated dome and the primary work of this dissertation are as follows:(1)A refined analytical member model based on initial curvature considering endmoments is proposed and the mechanics performance is refined analyzed considering P-δ effect.Two types of the member curvature functions are proposed proceed from the deflection equilibrium equations of the compression bars under different endmoments.Combined with the fiber elements in the ABAQUS software and the steel ductile damage model,a refined analytical member model is proposed by the multibeam method.The validity of the proposed member model is verified through some existing stable capacity tests and shaking table tests of the dome in diffirent grid forms.The results show that: compared with the existing initial curvature member model,the stability bearing capacity of the dome established by the proposed member model considering end-moments decreases by 10% approximately.The seismic dynamic response is different under earthquakes with different PGA,and the maximum increasing degree of seismic displacement can be more than double.(2)An unfavorable discrimination criterion of initial imperfection is proposed and seismic response of the dome considering high-order imperfection mode is refined analyzed.A structural dynamic analytical model considering the valid maximum percent of the members under major bending stress status is defined as the discriminant criterion of the most unfavorable imperfection mode proceed from theory of the continuous thin dome.A structural dynamic analytical model considering the highorder imperfection mode is proposed.The validity of the proposed structural model is verified through the existing consistent imperfection model and random imperfection model in diffirent grid forms.The results show that: the most unfavorable imperfection mode is a high-order mode in general.The most unfavorable high-order mode can be selected effectively and efficiently by the proposed discriminant criterion.Compared with the existing consistent imperfection model,the seismic response of the dome established by the proposed imperfection model increase obviously as well as the damage range.The larger the rise-span ratio,the larger the influence of the high modal on the dynamic response is.The maximum increasing degree of seismic displacement can be more than double.Choosing top 20 orders as the high orders considered range can ensure the nonliteral analysis results safer and the calculating costs less than random imperfection model.(3)A global damage assessment model based on the local grid index is proposed and the seismic damage rapid assessment in different performance levels is analyzed.The relations between local grid damage and the residual bearing capacity of the dome is derived proceed from theory of the continuous thin dome.A global damage assessment model of the dome based on the local grid index is proposed by fitting a large number of numerical results,when adopting the global damage assessment model as the structural response parameter.The three-dimensional sensitive frequencies is adopted as the seismic intensity parameter.And different performance levels of the dome under strong earthquake are categorizes and the dome seismic vulnerability curves in the logarithmic normal distribution are plotted.On the other hand,the effect of different lateral stiffness of the supporting system is discussed and the results show that: the proposed damage assessment model can truly reflect the maximum damage extent of different local grids so that it can effectively evaluate the residual bearing capacity of the dome,which have the best correlation than deformation index and energy index.It turns out that the cooperative effects of the supporting system must be considered when the lateral stiffness of the supporting system is relatively weak.(4)Based on the proposed damage assessment model,a multi-objective optimization of damage distribution of the single-layer reticulated dome under strong earthquake is analyzed.According to the basis of equal seismic performance concept,a double-controlled objective functions,which are the global stability index and the global damage index,are defined.And the multi-objective optimization of the dome damage distribution is studied by selecting member section as the variables.The global damage index,dynamic response and residual bearing capacity are analyzed before and after the optimization.The results show that: the damage extent local grids in different position has a great difference when single-layer reticulated dome is under strong earthquake excitation.The concentration phenomena of the dome damage distribution can be effectively identified by the proposed global damage index considering member important coefficient.The damage concentration distribution of the dome is effectively avoided and the damage distribution of different members is more uniform through the optimization.Therefore,the residual stability capacity of the damaged dome increased by 29% at most.