| Viscoelastic damping device is one of effective passive control methods.With the advantages of reliable performance, simple construction and low cost, viscoelastic damping device has wide application foreground. However, little has been reported about the viscoelastic materials used in building structure. From the recent studies, the viscoelastic materials used in building structure are always from the field of aerospace engineering. So, the problems of small loss factor, high applying frequency and inconsistency of the application environment between civil engineering field and aerospace engineering. Currently, viscoelastic damping devices are widely used diagonal brace and inverse brace in structures, which leads to the devices axial displacements less than or equal to the inter-story displacement, thus lowering the efficiency of energy dissipation. Novel braces of viscoelastic damping devices which are based on the Toggle-Brace-Damper and Scissors-Jack-Damper are larger than the structural drift. However, there are some limitations when the novel braces are used. Except for the difficulties in construction and instability and the high cost, no doors or windows can be set at the installed location for brace-type devices. So, carrying out research of the modification of viscoelastic materials is imperative, and it is also the viscoelastic damping wall which can consider architectural function and also can provide large damping and large stiffness. The main contents and achievements in this dissertation are as follows:1. The modifications of viscoelastic damping materials are investigated. (1) Aiming to get damping materials used in building structure, NBR polymers mixed with graphite powder are prepared by hybridization of inorganic minimum molecule. Through the evaluation system of loss factor and damping temperature region, polymers with high loss factor and large damping temperature region are obtained. (2) NBR/Norsorex polymers are prepared by blending of long chain polymers. Through the evaluation system of LA/TA, NBR/Norsorex polymers with high LA are obtained. (3) Research on physical properties such as tensile strength, elongation, and shore hardness are investigated. Results show that the test parameters of damping materials can meet the standard practice in the application of viscoelastic damping device.2. Four-Parameter M | K mechanical model is studied. (1) Four-Parameter M | K mechanical model is derived by parallel connection of classical Maxwell model and classical Kevin model. (2) By using dynamic frequency sweep and dynamic temperature sweep, the storage modulus and the loss modulus are obtained within a temperature region from 0℃ ～40℃ and frequency region from 1.6～100 Hz. Using the test results, Four-Parameter M | K mechanical model is evaluated. The assessment results indicates Four-Parameter M | K mechanical model can comparatively accurately simulate the trend of changes of the storage module and the loss module by less model parameters.Four-Parameter M I K mechanical model can also get mechanical parameters of every element participating in models function. M I K mechanical model is more successful for describing the dynamic mechanical properties and can be used to simulate and analyze the visco-elastic behavior of this new material.3. Experiment of mechanical properties of super large viscoelastic damping wall under shear loading along the transverse direction is developed. (1) The temperature effect of the viscoelastic damping material is firstly investigated by temperature scanning tests, which can characterize precisely the temperature dependence of the viscoelastic damping device. (2) The system of shear loading along the transverse direction is put forward and the experiments of mechanical properties of "5+4" super large viscoelastic damping wall (VDW) is developed using this system. (3) The curves of tan δ-T, G’-T and G"-T of the viscoelastic material and the force displacement hysteretic curves are obtained. In addition, dynamical performance, such as the maximum damping force, loss factor, equivalent damping coefficient, storage stiffness,loss stiffness, loss modulus, storage modulus of VDW are analyzed. The results show that the maximum damping force of this novel damping wall is up to 241.5 kN. The equivalent damping coefficient decreases with increase in frequency. The loss stiffness, loss factor and shear loss modulus also decrease with increase in displacement. The loss factor peak value obtained from scanning tests of the viscoelastic damping material is compared with that of the viscoelastic damping wall, and the difference between them is 0.025. The designed "5+4" viscoelastic damping wall therefore exhibits a good energy dissipation capacity in shear loading mode in the transverse direction.4. The control effect and dissipation property of viscoelastic damping wall are investigated. (1) The shaking table tests of scaled model of steel frame with viscoelastic damping wall is conducted. Effects on structural vibration mode of by viscoelastic damping wall are studied. The dynamic properties and structural responses (for instance, the control effect on acceleration and displacement) of the damper-added structure are obtained. (2) The tests include five conditions, such as 1234,124,134,234 and steel frame without dampers. Influencing effects of the maximum story drift and the maximum acceleration about five different arrangements are compared under El Centro wave. (3) SAP2000 simulation of damper-added structure is established, and the contrastive analysis is made between SAP2000 simulation and experimental results. All these studies indicate that the control effect on the maximum acceleration is remarkable under El Centro wave. The story drift beyond the values of standard on uncontrolled condition can be controlled effectively under 700gal El Centro wave. Except 2-4 floor, the control of midpoint displacement response of in the first floor is far better than the acceleration. The maximum acceleration and story drift for every floor are well controlled. To the five arrangements of viscoelastic damping wall, control effects of acceleration are superior to displacement. The control effect by 1234 arrangement is the best. A good agreement of simulation results by SAP2000 and test results is showed. In this aspect, the consistency of frame structure with viscoelastic damping wall is better than without viscoelastic damping wall. |
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