Papers by Keyword: Hysteretic Behaviour

Abstract: This paper presents the development of the system identification (SI) for the highly nonlinear piezoelectric patch actuator. The transfer function is determined by using the nonlinear least square (NLS) method after the direct measurements of input-output data are taken from the actuator that is installed on a well-equipped platform. The results were validated to ensure that the transfer function derived fits well with the experimental output.

Abstract: Abstract. Thermoelasic martensitic transformations are controlled by the local equilibrium of chemical and non-chemical free energy contributions (D and E being the dissipative and elastic energies, respectively). The derivatives of non-chemical free energies ( ) as a function of the transformed martensite fraction (ξ) can be expressed from the experimental data obtained from the temperature-elongation, temperature-resistance, etc hysteresis loops. This method, developed in our laboratory, was used for the investigation of non complete, partial thermoelastic transformation cycles. In the first set of experiments the subsequent cycles were started below the Mf temperature and the maximum temperature was decreased gradually from a value above Af (series U). In the second (L) set the cycles were started above the Af and the minimum temperature was gradually increased from a value below Mf. In the third (UL) set the minor loops were positioned into the centre of the two phase region (i.e. the cycling was made with an increasing T temperature interval with T0.5 and <0.5, respectively. On the other hand the d() functions show a maximum at about the central point of the sub-cycles, and deviate considerably from the d() function obtained from the full cycles. This is also reflected in the  dependence of the integral value of the dissipative energy, D(): its value for the partial loops is lower than the dissipative energy calculated from the full cycle for the same transformed fraction interval. An opposite tendency (i.e. higher values for the partial loops) was obtained for the integral value of the elastic energy, E. The relative values of the dissipated energies, D, (calculated from the areas of the minor loops and normalized to the area of the major loop) are not very sensitive to the details of the cycling process, i.e. they are very similar for all sets.

Abstract: This paper discusses results of experiments on blind bolted end plate joints to concrete-filled thin-walled steel tubular (CFTST) columns. Four exterior joints to CFTST columns subjected to cyclic loadings. A feature of this novel joint is the use of the blind bolts and extensions to these bolts into the concrete-filled square steel tubular column. Failure modes, moment-rotation hysteretic curves and energy consumption of the connections were analyzed. Further, the connection rigidity and ductility were also elevated by present specifications. The test results showed that the end plate type and the steel tube thickness affect the seismic behaviour of the typed blind bolted end plate joints. The proposed joint has reasonable strength, stiffness and ductility by taking reasonable end plate type, steel tube thickness and blind bolt anchorage; its ultimate connection rotation satisfies the ductility design requirements, and could be reliably and safety used in low-layer or multi-layer composite frames.

Abstract: Two 1:4 scale wall specimen was tested under cyclic load to determine its seismic behavior, the responses of the steel frame with GRC lath are studied such as the failure modes, hysteretic behavior, ductility, energy dissipation, and the experimental results were compared with the steel frame. The testing data analysis indicated that bearing capacity, lateral stiffness, ductility and energy dissipation of the steel frame with GRC light hollow lath are superior to the steel moment frame, the steel frame with GRC lath is an ideal lateral resistant system. The prolapse of GRC lath from the frame did not appear, so the steel frame with GRC lath could be better used in the earthquake zone. Due to the collapse of connection of lath with frame, the ductility coefficient of the system is generally between 2 and 3, it is less than requirement of the seismic design specifications, and therefore a suggestion is that the seismic design of steel frame with GRC lath can be according to non-filled wall frame structure.

Abstract: Flexible piers have been widely used in bridge engineering due to its superior ductility. The stirrup ratio and slenderness ratio were deemed to have a most important impact on hysteretic behavior of them. Five flexible piers were made under static vertical loads and low cyclic horizontal reversed loads. The process of test was introduced and failure mechanism, hysteretic behavior, skeleton curve, ductility, energy dissipation capacity, and stiffness degeneration of flexible piers were analyzed. Experimental studies show that (1) Failure mode of specimen is bending failure and their ductility factor falls between 4.15 and 6.30; (2) displacement ductility factor improves with increasing of the stirrup ratio. Stirrup could greatly improve the capacity on ductility and energy dissipation, while it has little impact on the bearing capacity; (3) ultimate bearing capacity decline with the increase of slenderness ratio, however, when the slenderness ratio member is larger, the hysteresis curve is fuller and energy-dissipation is better.

Abstract: To simulate the hysteretic behavior and propose the analytical model of steel reinforced concrete (SRC) columns under low cyclic loads, different fiber models which can reflect the mechanical behavior of materials are used in this paper. The unconfined concrete, partially confined concrete, highly confined concrete, structure steel and longitudinal reinforcement bars of the complex cross section can be established by OpenSees program which can define the different fibers for kinds of materials with their own stress-strain relations, respectively. Based on fiber models, the analytical model for simulating the hysteretic behavior of SRC columns is proposed. By comparing with the conventional simulation results, the results which are obtained from the proposed analytical model in this paper agree with the experimental results better.

Abstract: Overall 12 specimens were experimentally investigated in this paper to study the hysteretic behaviors of the concrete-filled circular CFRP-steel tubular (C-CFRP-CFST) beam-columns. The test results indicated that CFRP can provide transverse confinement effect and longitudinal strengthening effect for the concrete filled circular steel tubular (C-CFST) beam-columns effectively and the local buckling of the steel tube is deferred. With the increase of the strengthening factor of the longitudinal CFRP, the damage scale reduces.

Abstract: A model of full scale one-bay, one storey was tested under low cyclic loading in order to study the hysteretic behavior of steel frames with sandwich composite (SC) panels. According to the failure pattern and damage process of test specimen, seismic behaviors were evaluated. Hysterics loops, skeleton curves, curves of strength degradation, and curves of stiffness degradation, ductility index and viscous damping coefficient were analyzed. Test results show that the failures of panels mainly occurred around the embedded parts, but compared with traditional panels and walls, SC panels exhibit a better integration. The connection between panel and steel frame is vital to the mutual work of the two parts. Finally, seismic design recommendations based on the analysis of ductility index and energy dissipation of the structures are presented.

Abstract: The seismic performance of K-shape eccentrically frames were researched by cyclic loading test method, in order to understand earthquake performance, stiffness degradation and dissipation mechanism of energy. It can be concluded that K-shape eccentrically frames provide high elastic stiffness and demonstrate excellent energy dissipation capacity in the plastic stage, the different length of the link beam of different layers has great influence on the energy dissipation capacity of the structure, when shear yielding of link beam occurs, stiffness degradation become apparent, the hysteretic curves were plump in shapes. Therefore, K-shape eccentrically frames have better hysteretic behavior and energy dissipation capacity, the results can provide a reference for the engineering design and related research.

Abstract: The accumulative damage model in which the material’s plastic strain is defined as variable and the energy dissipation is also considered is applied to the combined welded heavy steel plates. And the reliability of the model is confirmed by comparing the computed results in finite element project ABAQUS to tested results from previous researcher. On that basis, a series of steel plate components are computed to analyze their hysteretic curves and ductility factors. The influences of steel plate thickness, web’s height-thickness ratio and flange’s width-thickness ratio on hysteretic behavior are studied.