Study On Wind Loads And Dynamic Parameters Identification Of Super Tall Building

One of the important indicators considered in the safety and suitability design of super tall buildings is the structural wind load and wind-induced response.Therefore,it is a very significant work for the research on the wind load and wind-induced response of the super tall buildings.Field measurement,wind tunnel test and numerical simulation are the three most commonly used methods for studying the characteristics of structures under wind load action.Although field measurement is the most reliable research method,they can only measure the response information of some floors.The loads cannot be obtained directly.Although the structural wind loads can be obtained by the wind tunnel test,the result is difficult to accurately reflect the true state of the structure under the action of the wind.Through the numerical simulation,the wind load at any point of the structure can be obtained its accuracy needs to be verified continuously.With the development of science and technology,the field measurement technology has gradually matured,and the dynamic response of the structure is easily measured.Therefore,based on the measured dynamic response,using the inverse identification method to identify the fluctuating wind load of all floors and the dynamic response of the untested layer on the input part of the floor response data has become a hot research topic in the field of wind engineering.The information of structural load and response can reflect the state of the structure under the action of wind,and can provide an important basis for structural health monitoring and wind resistance design.Therefore,it is necessary to propose a inverse analysis method to indirectly obtain comprehensive information of wind loads and responses on structures.In the field of structural engineering,the dynamic parameter of the structure is an important indicator for structural health monitoring and dynamic design.At present,the identification of structural parameters generally identifies structural modal parameters because conversion to modal space can make the calculation process easier.Under the action of load,the structural response information can directly reflect the change of its parameters.Therefore,the structural parameter identification method based on dynamic response is considered as one of the most effective ways to judge the structural damage.Based on the existing field measurement technology,It is especially important to propose a method of structural parameter identification when the structural partial response is known and the load information is unknown.Therefore,this paper proposes two wind load identification methods and three identification methods for structural parameters.Based on the Kalman filter theory,the second phase of the Hong Kong International Finance Center is used as the engineering background,and wind tunnel tests are used as a means to systematically study A time-domain method for identifying fluctuating wind loads and identifying structural parameters using wind-induced responses of limited test floors.The main research content is as follows:(1)In this paper,the method of augmenting matrix differential equations is used to solve the structural dynamic response under wind load.By constructing structural differential equations into the form of state space,the "order reduction" of matrix differential equations is achieved.Then the wind-induced response of the reduced matrix matrix is obtained and the influence of the initial state of the structural response on the response vector at time t is analyzed.;as a comparison,another calculation method,the Newmark-? method,is presented in this paper.The results of the two methods are compared and analyzed.According to the modal transformation theory and the super tall building wind-induced vibration characteristics,the problem of insufficient measurement points in the inverse analysis of super tall buildings was solved.The main control mode number and the minimum number of measurement points were determined according to the POD method.(2)By using modal transformation theory and wind vibration characteristics of super high-rise buildings,the problem of insufficient measurements in inverse analysis is solved.And according to POD method,the number of main control modes and the minimum number of measurements are determined.(3)Based on the discrete Kalman filter theory,two inversion methods(DKF,ADKF)for fluctuating wind loads are proposed.Firstly,the dynamic differential equation is tranformed into the state space equation,then the extended form of discrete Kalman filter for estimating wind load is deduced.Then the identification methed of the fluctuating wind load and unmeasured wind-induced response is obtained(DKF).The Augmented-discrete state Kalman filter method(A-DKF)is acqured through the augmention to sate space equation.The stability of the inverdion is determined by the spectral radius of matrix.And by introducing displacement dummy-measurement solves the unstable problem caused by the augmented system.To overcome the dependence of Kalman filter to the process and observation noise intensity,the L-curve method in regularization theory is introduced into inversion system to identify the most reasonable value of observation noise,meanwhile,the ability to resist noise and the applicability of the inversion algorithm are improved.(4)Based on the wind tunnel test,the feasibility and accuracy of the wind load inversion methods are verified,and wind loads and wind-induced responses on each floor are estimated by the two methods for response using only seven floors on(one of a displacement,velocity and acceleration),and the result is satisfactory.In addition,the accuracy of wind load inversion under various noise levels can meet the requirements of engineering practice,and the characteristics of the two methods are compared and analyzed.(5)By using the extended Kalman filter(EKF)algorithm and its two improved methods,adaptive extended Kalman filter algorithm(AEKF),moving-window extended Kalman filter algorithm(MWEKF),inputing displacement response of limited floors,the frequency and damping ratio of the structure are identified.The results show that in the input displacement response,the above three methods can better identify the parameters of the structure.AEKF can improve the stability of the filter and make the recognition result more stable,MWEKF is not sensitive to the selection of initial state vector and initial value of estimation error covariance.It does not depend on the assumed noise level,because process noise and measurement noise can be estimated,and it can also maintain its optimality when the process noise is nonstationary.