This paper is concerned with investigation of the dynamic behaviors of cranes under seismic effects. For this purpose, firstly we have performed experiment on a 1/20 scale crane model on the shake table with real earthquake data, then a multi degree-of-freedom non-linear mathematical model is developed including behavior of the container cranes under earthquakes and simulated. The simulation system has a five degrees-of-freedom and modeled system was simulated for the ground motion of the El Centro earthquake in USA, 1940. Finally, the time history of the crane bridge displacement and acceleration responses of the both theoretical and experimental cases are presented. Theoretical and experimental results exhibit that the mathematical model is accurate. This study also shows the destructive effects of high accelerations which occur during the earthquake. These effects cannot be omitted in the design of cranes. The result of this study which is an accurate mathematical model can be inspiring for the engineers in terms of design parameters.

This paper is concerned with the verification of mathematical modeling of the container cranes under earthquake loadings with shake table test results. Comparison of the shake table tests with the theoretical studies has an important role in the estimation of the seismic behavior of the engineering structures. For this purpose, a new shake table and mathematical model were developed. Firstly, a new physical model is directly fixed on the shake table and the seismic response of the container crane model against the past earthquake ground motion was measured. Secondly, a four degrees-of-freedom mathematical model is developed to understand the dynamic behaviour of cranes under the seismic loadings. The results of the verification study indicate that the developed mathematical model reasonably represents the dynamic behaviour of the crane structure both in time and frequency domains. The mathematical model can be used in active-passive vibration control studies to decrease structural vibrations on container cranes.

No abstract

This paper studies the design of a state-feedback delay-dependent H ∞ controller for vibration attenuation problem of a seismic-excited container crane subject to having time-varying actuator delay, L 2 type disturbances and actuator saturation. First, a sufficient delay-dependent stability criterion is developed by choosing a Lyapunov-Krasovskii functional candidate based on matrix inequalities for a stabilizing H ∞ synthesis. To convexify the Bilinear Matrix Inequality (BMI) based optimization problem involved in the delay dependent conditions; a cone complementary linearization method is adopted to find a sub-optimal solution. The proposed method also utilizes convex description of nonlinear saturation phenomenon by means of convex hull of some linear feedback which leads to a few additional ellipsoidal conditions in terms of Linear Matrix Inequalities (LMIs). By use of the proposed method, a suboptimal controller with maximum allowable delay bound and minimum allowable disturbance attenuation level can be easily obtained by a convex optimization technique. In order to show effectiveness of the proposed approach, a five Degrees-of-Freedom (DOF) container crane structure is modeled using a spring-mass-damper subsystem. The system is then simulated against the real ground motions of Kobe and Northridge earthquakes. Finally, the time history of the crane parts displacements, accelerations, control forces and frequency responses of the both uncontrolled and controlled cases are presented. Additionally, the performance of the proposed controller is also compared with a nominal state-feedback H ∞ controller performance. Simulation results show that, in spite of the actuator saturation, the designed controller is all effective in reducing vibration amplitudes of crane parts and guarantees stability at maximum actuator delay.

Self-tuning fuzzy logic controllers (STFLC) for the active control of Marmara Kocaeli Earthquake excited crane structures are studied in this paper. Vibration control using intelligent controllers, such as fuzzy logic has attracted the attention of structural control engineers during the last few years, because fuzzy logic can handle, uncertainties and heuristic knowledge and even non-linearities effectively and easily. The improved seismic control performance can be achieved by converting a simply designed static gain into a real time variable dynamic gain through a self-tuning mechanism. A self-tuning fuzzy logic controller is designed to reduce the vibrations of the crane structure. The simulated system has a five degrees-offreedom and modeled system was simulated against the ground motion of the Marmara Kocaeli Earthquake (M w = 7.4) in Turkey on August 17, 1999. At the end of the study, the time history of the crane bridge and portal legs displacements, accelerations, and frequency responses of the both uncontrolled and controlled cases are presented. Additionally, the performance of the designed STFLC is also compared with a PD controller. Simulations of an earthquake excited bridge and portal legs are performed to prove the validity of proposed control strategy.