• 한국공간구조학회논문집
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• 제4권4호
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• pp.65-76
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• 2004

Walking loads are usually considered as nodal loads in the finite element vibration analysis of structures subjected to walking loads. Since most of the walking loads act on elements not nodes, the walking loads applied on the elements should be converted to the equivalent nodal walking loads. This paper begins with measuring walking loads by using a force plate equipped with load cells and investigates the characteristics of the walking loads with various walking rates. It is found that the walking loads are more affected by walking rates than other parameters such as pedestrian weight, type of footwear, surface condition of floor etc. The measured walking loads are used as input loads for a finite element model of walking induced vibration. Finally, this paper proposes the equivalent nodal walking loads that are converted from the walking loads acting on elements based on finite element shape functions. And the proposed equivalent walking loads are proved to be applicable for efficient analysis of floor vibration induced by walking loads.

• Earthquakes and Structures
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• 제5권5호
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• pp.589-605
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• 2013

The effect of dead loads on dynamic responses of a uniform elastic beam subjected to moving loads is examined by means of a governing equation which takes into account initial bending stresses due to dead loads. First, the governing equation of beams which includes the effect of dead loads is briefly presented from the author's paper (1990, 1991, 2010). The effect of dead loads is considered by a strain energy produced by conservative initial stresses caused by the dead loads. Second, the effect of dead loads on dynamical responses produced by moving loads in simply supported beams is confirmed by the results of numerical computations using the Galerkin method and Wilson-${\theta}$ method. It is shown that the dynamical responses by moving loads are decreased remarkably on a heavyweight beam when the effect of dead loads is included. Third, an approximate solution of dynamic deflections including the effect of dead loads for a uniform beam subjected to moving loads is presented in a closed-form for the case without the additional mass due to moving loads. The proposed solution shows a good agreement with results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. Finally it is clarified that the effect of dead loads on elastic uniform beams subjected to moving loads acts on the restraint of the transverse vibration for the both cases without and with the additional mass due to moving loads.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.459-466
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• 2001

The floor vibration aspect for building structures which are in need of large open space are influenced by the interrelation between natural frequency and working loads. Structures with a long span and low natural frequency have a higher possibility of experiencing excessive vibration induced by dynamic excitation such as human activities. These excessive vibrations make the residents uncomfortable and the serviceability deterioration. Need formulation of loads data through actual measurement to apply walking loads that is form of dynamic load in structure analysis. The loads induced by human activities were classified into two types. First type is in place loads. the other type is moving loads. A series of laboratories experiments had been conducted to study the dynamic loads induced by human activities. The earlier works were mainly concerned to parameters study of dynamic loads. In this Paper, the walking loads have been directly measured by using the measuring plate in which two load cells were placed, the parameters, the load-time history of walking loads, and the dynamic load factors have been analyzed. Moreover, the shape of the harmonic loads which were gotten by decomposition the walking loads have been analyzed , and the walking loads modeling have been carried out by composition these harmonic loads derived by functional relation.

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.761-781
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• 2012

The collapse of structures due to snow loads on roofs occurs frequently for steel structures and rarely for reinforced concrete structures. Since the most significant difference between these structures is related to their ability to handle dead loads, dead loads are believed to play an important part in the collapse of structures by snow loads. As such, the effect of dead loads on displacements and stress couples produced by live loads is presented for plates with different edge conditions. The governing equation of plates that takes into account the effect of dead loads is formulated by means of Hamilton's principle. The existence and effect of dead loads are proven by numerical calculations based on the Galerkin method. In addition, a closed-form solution for simply supported plates is proposed by solving, in approximate terms, the governing equation that includes the effect of dead loads, and this solution is then examined. The effect of dead loads on static live loads can be explained explicitly by means of this closed-form solution. A method that reflects the effects of dead loads on live loads is presented as an example. The present study investigates an additional factor in lightweight roof structural elements, which should be considered due to their recent development.

• 한국전산구조공학회논문집
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• 제15권1호
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• pp.173-188
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• 2002

보행하중을 받는 바닥판 구조물의 진동해석을 위해서 일반적으로 계측한 보행하중을 적용하거나 Bachmann의 보행하중식을 사용하게 된다. 다양한 매개변수의 영향을 받는 보행하중은 계측이 쉽지 않으며 Bachmann 보행하중식은 보행진동수가 2.OHz와 2.4Hz로 제한적이기 때문에 다양한 보행진동수에 따른 보행하중을 적용하기가 곤란하다. 따라서 보행하중을 받는 구조물의 진동해석을 위해서 보행하중의 매개변수 분석과 다양한 보행진동수에 적용이 가능한 보행하중의 모형화가 필요하다. 본 논문에서는 로드셀이 장착된 계측 플레이트를 이용하여 바닥판에 가해지는 보행하중을 직접 계측하고 매개변수를 분석하였다. 그리고 퓨리에 변환을 이용하여 계측한 보행하중을 다양한 진동수를 가지는 조화하중으로 분해하였다. 분해과정을 거쳐 얻은 조화하중의 계수들을 보행진동수에 대한 일정한 함수관계로 유도하여 보행하중을 모형화하였다. 본 논문에서 제안한 보행하중식을 이용하면 다양한 보행진동수에 따라 다르게 나타나는 보행하중을 구조물의 진동해석에 용이하게 적용할 수 있다.

• Earthquakes and Structures
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• 제1권4호
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• pp.411-425
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• 2010

The effect of dead loads on dynamic responses of uniform elastic beams is examined by means of a governing equation which takes into account initial bending stress due to dead loads. First, the governing equation of beams which includes the effect of dead loads is briefly presented from the author's paper (Takabatake 1990). In the formulation the effect of dead loads is considered by strain energy produced by conservative initial stresses produced by the dead loads. Second, the effect of dead loads on dynamical responses produced by live loads in simply supported beams and clamped beams is confirmed by the results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. It is shown that the dynamical responses, like dynamic deflections and bending moments produced by dynamic live loads, are decreased in a heavyweight beam when the effect of dead loads is included. Third, an approximate solution for dynamic deflections including the effect of dead loads is presented in closed-form. The proposed solution shows good in agreement with results of numerical computations with the Galerkin method and Wilson-${\theta}$ method. Finally, a method reflecting the effect of dead loads for dynamic responses of beams on the magnitude of live loads is presented by an example.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.273-280
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• 2000

Building structures which are in need of large open space make the damping effect of the structures decrease greatly. Assembly and office buildings with a lower natural frequency have a higher possibility of experiencing excessive vibration induced by human activities. These excessive vibration make the residents uncomfortable and the serviceability deterioration. The loads induced by human activities were classified into two types. First type is in place loads as like jumping, foot stamping and body bouncing. The other type is moving loads as like walking, running and dancing. A series of laboratories experiments had been conducted to study the dynamic loads induced by human activities, The earlier works were mainly concerned to parameters study of dynamic loads as like activity type, weight, sex, surface condition of structure and etc. In this paper, we have measured directly the walking loads by using the platform. And we have evaluated and analyzed load-time history of walking loads. One of the most important parameter is pacing rate (walking speed) in the walking loads. The difference between the maximum value and minimum value of walking loads depends on the walking speed.

• 한국항공운항학회지
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• 제19권4호
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• pp.67-73
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• 2011

For loads analysis of airplane, applicable regulation should be determined. Then, loads conditions are prepared from the regulation. Modeling for aerodynamic, mass, and structure are performed. Panel method is usually adopted for aircraft loads analysis to obtain air loads. The ARGON which is a multidisciplinary fixed wing aircraft design software co-developed by the KARI and TsAGI are used for loads analysis. The ARGON can be utilized for flutter and stress analysis as well as for flight and ground loads analysis. In this paper, flight loads analysis for wing structural design of the regional aircraft at the conceptual design phase are performed with the ARGON. FAR 25 is used for the regulation for the load analysis. Shear force, bending moment and torsion diagrams for the wing and shear force and hinge moment for the aileron are presented.

• 풍력에너지저널
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• 제5권1호
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• pp.43-49
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• 2014

Primarily, tower loads of a wind turbine arise from aerodynamic effect and a top head mass. But sometime asymmetric loads of rotor also affect on the tower loads. Especially ice formation on two blades out of three causes the asymmetric loads, because the ice formation on blades lead to large rotating mass imbalance. This rotating mass imbalance of rotor affects tower fatigue loads. So design load cases of ice formation on blade should be considered in the fatigue design loads of the tower according to GL guideline 2010. This paper describes the change of tower fatigue loads following increase of tower height in the condition of ice formation. Finally, the optimal operation strategy is examined in order to reduce tower fatigue design loads.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.551-564
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• 2016

High-speed flight vehicles (HSFVs) such as space launch vehicles and missiles undergo severe dynamic loads which are generated during the launch and in in-flight environments. A typical vehicle is composed of thin plate skin structures with high-performance electronic units sensitive to such vibratory loads. Such lightweight structures are then exposed to external dynamic loads which consist of random vibration, shock, and acoustic loads created under the operating environment. Three types of dynamic loads (acoustic loads, rocket motor self-induced excitation loads and aerodynamic fluctuating pressure loads) are considered as major components in this study. The estimation results are compared to the design specification (MIL-STD-810) to check the appropriateness. The objective of this paper is to study an estimation methodology which helps to establish design specification for the dynamic loads acting on both vehicle and electronic units at arbitrary locations inside the vehicle.