• Journal of Institute of Control, Robotics and Systems
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• v.7 no.10
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• pp.812-818
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• 2001

This paper proposes an optimum design method of structural and control systems, taking a 2-D truss structure as an example. The structure is supposed to be subjected to initial static loads and disturbances. For the structure, a FEM model is formed, and using modal transformation, the equation of motion is transformed into that of modal coordinates in order to reduce the D.O.F. of the FEM model. The structure is controlled by an output feedback $H^$\infty$$ controller to suppress the effect of the disturbances. The design variables of the simultaneous optimal design of control-structure systems are the cross sectional areas of truss members. The structural objective function is the structural weight. The control objective function is the $H^$\infty$$ norm, that is, the performance index of control. The second structural objective function is the energy of the response related to the initial state, which is derived from the time integration of the quadratic form of the state in the closed-loop system. In a numerical example, simulations have been carried out. Through the consideration of structural weight and $H^$\infty$$ norm, an advantage of the simultaneous optimum design of structural and control systems is shown. Moreover, while the optimized performance index of control is almost kept, we can acquire better design of structural strength.

• Journal of Ship and Ocean Technology
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• v.5 no.2
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• pp.14-26
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• 2001

This paper presents a novel design approach that could generate structural design alternatives having different topologies and then, select the optimum structure from them with simulataneously determining its optimum design variables related to geometry and the member size subjected to the multiple objective design environments. For this purpose, a specialized genetic algorithm, called StrGA_DeAl + MOGA, which can handle the design alternatives and multi-criteria problems very effectively, is developed for the optimal structural design. To validate the developed method, method, plain truss design problems are considered as illustrative example. To begin with, some possible topological of the truss structure are suggested based on the stability criterion that should be satisfied under the given loading condition. Then, with the consideration of the given multi-criteria, several different topology forms are selected as design alternatives for the second step of the conceptual design process. Based on the chosen topolgy of truss structures, the sizing or shaping optimization process starts to determine the optimum design parameters. Ten-bar truss problems are given in the paper to confirm the above concept and methodology.

• Structural Engineering and Mechanics
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• v.43 no.6
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• pp.711-724
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• 2012

The goal of this study is to conceptually orientate optimized layouts of outrigger belt trusses which are in widespread use today in the design of tall buildings by strut-and-tie truss models utilizing a topology optimization method. In this study unknown strut-and-tie models are realized by using a typical SIMP method of topology optimization methods. In tradition strut-and-tie model designs find the appropriate strut-and-tie trusses along force paths with respect to elastic stress distribution, and then engineers or designers determine the most proper truss models by experience and intuition. It is linked to a trial-and-error procedure based on heuristic strategies. The presented strut-and tie model design by using SIMP provides that belt truss models are automatically and robustly produced by optimal layout information of struts-and-ties conforming to force paths without any trial-and-error. Numerical applications are studied to verify that outrigger belt trusses for tall buildings are optimally chosen by the proposed method for both static and dynamic responses.

• Computational Structural Engineering
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• v.10 no.3
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• pp.195-202
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• 1997

The charateristics of stabilization for stabilized truss unit-structures with cable and truss are investigated in this paper. This unit system is composed of a central post and eight cables, and is connected by hinge joints, and stabilized by self-equilibrated stress field. As this unit structure itself is a statically closed and stabilized system individually, it can be employed to assemble structures with various configurations. In this study, for stabilization of truss structures stabilized by cable tension, the structural concept of unit structures, the range of various geometrical parameters and the relationship of governing parameters about unit systems are explained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.10 s.181
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• pp.2502-2512
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• 2000

Truss structures are widely used in many space structures, such as large antenna systems, space stations, precision segmented telescopes because they are light in weight and amenable in assembly or deployment. But, due to the low damping capacity, they remain excited for a long time once disturbed. These structural vibrations can reduce life of the structures and cause unstable dynamic characteristics. In this research, vibration suppression experiment has carried out with a three-dimensional 15-member truss structure using two piezoelectric actuators. Piezoelectric actuators which consist of stacks of thin piezoelectric material disks are directly inserted to the truss structure collocated with the strain sensors. Each actuator is controlled digitally in decentralized manner, based on local integral and proportional feedback. The optimal positions of the actuators are determined by the modal damping ratio and the control force. Numerical simulation has carried out to determine optimal position of each actuator.

• Journal of Korean Association for Spatial Structures
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• v.10 no.4
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• pp.59-66
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• 2010

This study presents the topology optimization technique by density method to determine the initial shape of space truss structures. Most initial shape design is performed by designer's previous experiences and trial and error method instead of the application of reasonable optimization method. Thus, the reasonable and economical optimization methods are needed to be introduced for the initial shape design. Therefore, we set design domain for cantilever space truss structure as an example model. And topology optimization is used to obtain optimum layout for them, and then size optimization method is used to find the optimum member size. Therefore, the reasonable initial optimal shapes of spatial truss structures can be obtained through the topology and size optimization using density method.

• Earthquakes and Structures
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• v.19 no.6
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• pp.459-469
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• 2020

An external prestressed steel-bar truss unit was developed as a new strengthening technology to enhance the seismic performance of an in-plane masonry wall structure while taking advantage of the benefits of a prestressed system. The presented method consists of six steel bars: two prestressed vertical bars to introduce a prestressing force on the masonry wall, two diagonal bars to resist shear deformation, and two horizontal bars to maintain the configuration. To evaluate the effects of this new technique, four full-scale specimens, including a control specimen, were tested under combined loadings that included constant-gravity axial loads and cyclic lateral loads. The experimental results were analyzed in terms of the shear strength, initial stiffness, dissipated energy, and strain history. The efficiency of the external prestressed steel-bar truss unit was validated. In particular, a retrofitted specimen with an axial load level of 0.024 exhibited a more stable post behavior and higher energy dissipation than a control specimen with an observed complete sliding failure. The four vertical bars of the adjacent retrofitting units created a virtual column, and their strain values did not change until they reached the peak shear strength. The shear capacity of the masonry wall structure with external prestressed steel-bar truss units could be predicted using the model suggested by Yang et al.

• Structural Monitoring and Maintenance
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• v.5 no.1
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• pp.79-92
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• 2018

The evaluation theory of reliability, availability, maintainability and safety (RAMS) as a mature theory of state evaluation in the railway engineering, can be well used to the evaluation, management, and maintenance of complicated structure like the long-span bridge structures on the high-speed railway. Taking a typical steel-truss arch bridge on the Beijing-Shanghai high-speed railway, the Nanjing Dashengguan Yangtze River Bridge, this paper developed a new method of state evaluation for the existing steel-truss arch high-speed railway bridge. The evaluation framework of serving state for the bridge structure is presented based on the RAMS theory. According to the failure-risk, safety/availability, maintenance of bridge members, the state evaluation method of each monitoring item is presented. The weights of the performance items and the monitoring items in all evaluation levels are obtained using the analytic hierarchy process. Finally, the comprehensive serving state of bridge structure is hierarchical evaluated.

• Structural Engineering and Mechanics
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• v.13 no.2
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• pp.231-239
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• 2002

The problem of dynamic analysis of truss structures based on probability is studied in this paper. Considering the randomness of both physical parameters (elastic module and mass density) of structural materials and geometric dimension of bars respectively or simultaneously, the stiffness and mass matrixes of the elements and structure have been built. The structure dynamic characteristic based on probability is analyzed, and the expressions of numeral characteristics of inherence frequency random variable are derived from the Rayleigh's quotient. The method of structural dynamic analysis based on probability is developed. Finally, two examples are given.

• Journal of Korean Association for Spatial Structures
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• v.22 no.3
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• pp.15-24
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• 2022

In this research, the case of modern wooden structures since 1950 with span of 30m or more was investigated and analyzed the construction status and structural planning characteristics of wooden large space architecture. As a result, wooden large space buildings have built around Asia, North America, and Europe, in which cases of ice skating stadiums with span of 30m to 60m were concentrated. In the case of baseball parks and football stadiums, even a span of about 165m was built in a wooden structure. In addition, it was found that the structural systems used in wooden large space structures were a funicular arch and truss structure, in that cases, funicular arch system consisting of radial arrangements was used in the examples exceeded 150m and the two way truss system was also used in long span wooden structures exceeding 100m. As the truss structure with a tie-rod or the flexure+tension structure was partially investigated, it can be seen that various timber structural systems need to be devised and researched. Also, It was investigated that a technique in which some members of the truss are made of steel or a composite member of steel and timber is also possible to develop