Human-induced Vibration Serviceability Assessment Of The Assembled Floor Based On The Full Path Of The Source-path-receiver

With the development of materials,lightweight and high-strength materials are widely used in recent years,and many lightweight structures,such as CFS composite floor,pedestrian bridge,etc.,are increasingly constructed.With the wide spread of assembled structure,the material of assembled floor is more and more dependent on light and high-strength materials.For light floor,its mass is 150 kg/m~2 or less,and its quality is only1/2 to 1/3 of that of concrete floor.Furthermore,the frequency of light floor is close to that of pedestrians,which easily leads to the problem of human-induced vibration serviceability.Compared with cast-in-situ floors,fabricated floors have weakened boundary conditions and lower frequency,which make them more sensitive to pedestrian loads.Vibration serviceability will be an important factor affecting the use of fabricated floors.In most current design codes,the method of estimating the vertical vibration amplitude of floor caused by human-induced excitation only regards the pedestrian action on the floor as pedestrian load,but there are few studies considering the human-floor interaction,especially for lightweight floor with lower frequency,which is more obvious than ordinary floor.For serviceability evaluation,the peak acceleration of the structure under source-path is considered as the criterion to evaluate the vibration serviceability.In practical engineering applications,this method is more convenient and direct.However,the dynamic response of the structure under source-path is replaced by the dynamic response of the real serviceability receiver(human)under the whole source-path-receiver path,which assumes that the receiver acting on the structure is a rigid body rather than a dynamic system.Because human is the only perception body of serviceability,it is obviously inaccurate to evaluate human vibration serviceability only by taking structural response as the evaluation index.In order to accurately evaluate the vibration serviceability of assembled lightweight floors,a framework for evaluating the vibration serviceability of assembled lightweight floors based on source-path-receiver full path is proposed in this paper,taking into account the human-structure interaction on the basis of previous studies.The source-path-receiver coupled vibration control equation is established and processed by DQ-IQ mixing method.Then the acceleration response of the floor and the receiver can be obtained by Newmark method,and the vibration serviceability of the structure can be evaluated by probability method.The vibration serviceability of the assembled floor can be improved by semi-rigid constraint.The excessive vibration is controlled by tuned mass damper using serviceability evaluation index.The main contents of this paper include the following aspects:(1)In order to analyze the vertical vibration modes of CFS composite floor under different boundary conditions without excitation,the differential quadrature method(DQ)is used to solve the free vibration response of the plate.The free vibration equation of a plate is a fourth-order partial differential equation about X and Y.The differential quadrature method is used to transform the vibration equation into a second-order partial differential equation.The frequency characteristic equation of the plate can be obtained by degenerating the equation.The mode shapes and natural frequencies of the plate are obtained and compared with those of the existing literature,the accuracy of the DQ method is illustrated,and the first four modes are drawn.The vibration shape diagram can provide the basis for the installation point of the TMD in the vibration control of the floor.(2)The semi-rigid boundary condition is used to realize the assembly floor,and the serviceability of the floor is improved by adjusting the stiffness ratio.In order to evaluate the vibration serviceability of assembled floor under pedestrian load,the differential quadrature(DQ)-integral quadrature(IQ)mixing method is used to solve the vibration response of the floor under pedestrian load.DQ-IQ mixing method and mode decomposition method are used to calculate the response of assembled floor under different walking step frequencies,and the serviceability degree of the floor is evaluated by probability method.(3)Considering the human-structure interaction,the coupled vibration control equation of pedestrian-floor interaction is established,and the acceleration response of the floor is obtained.The vibration serviceability of the assembled lightweight floor is accurately evaluated.The evaluation results are given in the form of probability,and the vibration serviceability of the floor is improved by semi-rigid constraints.When considering the requirement of vibration serviceability of assembled floor,the selection of semi-rigid restraint coefficient can be used as a reference in design.(4)In order to accurately evaluate the vibration serviceability of lightweight floor,a frameworkofhuman-inducedvibrationserviceabilityassessmentbasedon source-path-receiver full path is proposed on the basis of previous research.The source-path-receiver coupled vibration control equation is established.Taking CFS composite floor with light weight and dense modes as an example,when pedestrians pass through the floor at normal walking frequency,the dynamic response of the floor and 60 receivers is analyzed.Finally,the serviceability of the floor and receivers is evaluated by probability method.(5)Based on the full path of source-path-receiver,the vibration serviceability of assembled floor is evaluated more accurately.For assembled composite lightweight floor,due to different boundary conditions,the stiffness of the floor can be adjusted,which affects the response of human-induced vibration,and then changes the serviceability of the floor.Considering the human-structure interaction,the acceleration response in the span of the floor is compared with the acceleration response of the receiver.The serviceability of the floor and the receiver is evaluated by probability,and the serviceability of the floor is improved by adjusting the stiffness coefficient.(6)According to the evaluation criteria of floor serviceability,the technical specification for high-rise concrete structures(JGJ3-2010)clearly stipulates that the floor structure should have appropriate serviceability,and the peak value of vertical vibration acceleration should not exceed 0.05m/s~2 in office environment.Then the control equation considering the interaction of source-path-receiver-TMD is established,and the vibration reduction effect of the floor and the receiver is compared by using a single TMD to control the vibration.