In this study the characteristics of wind pressure that are depending on the open type of retractable dome roof were analyzed according to the wind pressure coefficient and wind pressure spectrum. The analysis results showed that the open type and shape of the roof both had a significant impact on the wind pressure changing. In case of the edge to center open type, the wind pressure has not changed much because of the complex turbulence of flow and open area. On the other hand, in case of the center to edge open type, it has confirmed that wind pressure increases due to the separation of flow in windward and open area.
In this paper, the effect of the turbulence intensity in across-wind direction on the wind load in CFD(Computational fluid dynamics) simulation was analyzed. ‘Ansys fluent’ software was used for CFD simulation. And the fluctuating wind speed applied to the simulation was generated according to Korean Design Standard and Von Karman wind turbulence model. The turbulence intensity in across-wind direction for simulation was applied from 0 to 100% of the turbulence intensity in along-wind direction. The analysis results showed that the turbulence intensity in across-wind direction had a particularly great effect on the wind load in across-wind direction.
This paper describes a novel zero-stress member selecting method for sizing optimization of truss structures. When a sizing optimization method with static constraints is implemented, the member stresses are affected sensitively with changing the variables. However, because some truss members are unaffected by specific loading cases, zero-stress states are experienced by the elements. The zero-stress members could affect the computational cost and time of sizing optimization processes. Feature selection approaches can be then used to eliminate the zero-stress member from the whole variables prior to the process of optimization. Several numerical truss examples are tested using the proposed methods.
The U-flanged truss hybrid beam is a new composite beam made by pouring concrete into the U-flanged truss beam. In this study, an experimental study was performed to verify the shear capacity of U-flanged truss hybrid beams with the newly developed end reinforcement details. For all specimens, the maximum shear strength was determined by shear failure of concrete in the loading point The detail reinforced with stirrups at the end zone can exhibit the greatest shear strength, but the method of reinforcing the end zone using vertical steel plates, which is a relatively easy method to manufacture, is considered to be the most effective detail in terms of shear strength and ductility. Also, in the case of U-flanged truss hybrid beams reinforced with vertical steel plates at the end zone, the shear strength can be evaluated on the safety side by using the Korea Design Standard formula.
Control performance of a smart tuned mass damper (TMD) mainly depends on control algorithms. A lot of control strategies have been proposed for semi-active control devices. Recently, machine learning begins to be applied to development of vibration control algorithm. In this study, a reinforcement learning among machine learning techniques was employed to develop a semi-active control algorithm for a smart TMD. The smart TMD was composed of magnetorheological damper in this study. For this purpose, an 11-story building structure with a smart TMD was selected to construct a reinforcement learning environment. A time history analysis of the example structure subject to earthquake excitation was conducted in the reinforcement learning procedure. Deep Q-network (DQN) among various reinforcement learning algorithms was used to make a learning agent. The command voltage sent to the MR damper is determined by the action produced by the DQN. Parametric studies on hyper-parameters of DQN were performed by numerical simulations. After appropriate training iteration of the DQN model with proper hyper-parameters, the DQN model for control of seismic responses of the example structure with smart TMD was developed. The developed DQN model can effectively control smart TMD to reduce seismic responses of the example structure.
The purpose of this paper is to improve the inappropriate analysis results when the end of the brace on braced frame is applied as pinned connection in practice. The stiffness of the gusset plate connection on the braced frame has the amount of between pinned and rigid connection, and the analysis model that applies the stiffness of the connection must be used for accurate performance evaluation. In this study, the stiffness of the gusset plate designed by the balanced design procedure are quantified, and applied to the analysis model to simulate the gusset plate connection. The proposed model was verified through nonlinear static analysis (pushover analysis) of SAP2000. The effect of the connection on the seismic performance of the braced frame was analyzed by comparing the proposed model and pinned model. As a result, it was confirmed that the performance of the braced frame was evaluated conservatively in practice, and the ductility was overestimated. Therefore, it is important to consider the connection for accurate and economical performance evaluation.
As people's living standards and cultural standards have developed, interest in culture and art has increased, and the demand for large space structures where people can enjoy art, music, and sports has increased. As it accommodates a large number of personnel, it is most important to ensure safety of large spatial structures, and can be used as a space where people can evacuate in case of a disaster. Large spatial structures should be prepared for earthquake loads rather than wind loads. In addition to damage to the structure due to earthquakes, there are cases in which it was not utilized as a space for evacuation due to the fall of objects installed on top of the structure. Therefore, in this study, the dome-shaped large spatial structure is generalized and the displacement response according to the number of installations, position and mass is analyzed using a tuned mass damper(TMD) that is representative vibration control device.
In this paper, the dynamic response was analyzed by performing linear dynamic analysis using historic earthquake loads on twisted-shaped structures and fixed structure among free-form high-rise structures with atypical elevation shape following prior studies. In addition, the dynamic characteristics of the analysis models according to the plane rotation angle of the twisted structure were compared and analyzed. As a result of the analysis, as the plane rotation angle of the twisted structure increased, the interlayer deformation rate increased in the high-rise part of 50th floors or more. The story shear force and the story absolute acceleration were similar in the entire structure. In the case of the story shear force, the response of the twisted shape model was rather reduced in the middle part. As a result of analyzing the dynamic response, the vulnerable layer where the response amplification of the twisted structure occurs was found to be 31st story.