• Structural Engineering and Mechanics
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• v.9 no.3
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• pp.305-321
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• 2000

This paper develops a simplified, but effective, algorithm in obtaining critical slab design moments for parking garages. Maintaining the uniformly distributed load concept generally adopted in the design of building structures, this paper also introduces the equivalent vehicle load factors, which can simulate the vehicle load effects without taking additional sophisticated numerical analyses. After choosing a standard design vehicle of 2.4 tons through the investigation of small to medium vehicles made in Korea, finite element analyses for concentrated wheel loads were conducted by referring to the influence surfaces. Based on the obtained member forces, we determined the equivalent vehicle load factors for slabs, which represent the ratios for forces under vehicle loads to these under uniformly distributed loads. In addition, the relationships between the equivalent vehicle load factors and sectional dimensions were also established by regression, and then used to obtain the proper design moments by vehicle loads. The member forces calculated by the proposed method are compared with the results of four different approaches mentioned in current design codes, with the objective to establish the relative efficiencies of the proposed method.

• Computational Structural Engineering
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• v.10 no.3
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• pp.203-216
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• 1997

The Equivalent vehicle load factors of Beams and Girders on parking garage structure are proposed in this study. Without taking the sophisticated numerical analysis for the concentrated wheel loads, the design member forces of beam and girder can be easily calculated only with those for the distributed load by using the constructed relationships between the equivalent vehicle load factor and the length of member. Besides, the standard vehicle with total weight of 2.4ton is designed based on the review of many foreign design codes for parking garage and the investigation of small to medium vehicles made in Korea. Finally the efficiency and the reliability of the proposed equivalent vehicle load factors are demonstrated through the application of the typical beam and girder.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.131-138
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• 1997

The equivalent vehicle load factors which can consider the concentrated wheel load effect in slab design of parking garage structure are proposed. Based on the standard vehicle with total weight of 2.4 ton which is designed through the investigation of small to medium vehicle produced in Korea and the review of numerous foreign design codes for parking garage structure, the effects of moving vehicle loads on slab are analyzed using the finite element method. Besides. the relationships between the equivalent load factors and the sectional dimensions are established by regression analysis. The calculation of design forces can be easily accomplished without taking sophisticated numerical analysis for the moving vehicle load as the results obtained to the distributed load are multiplied by the proposed load factors in practice.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.04a
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• pp.233-240
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• 2002

In this paper, the effects of vehicle loads on flat slab system are investigated on the basis of the previous studies for beam-girder parking structural system. The influence surfaces of flat slab for typical design section are developed for the purpose of obtaining maximum member forces under vehicle loads. In addition, the equivalent vehicle load factors for flat slab parking structures are suggested using artificial neural network. The network responses are compared with the results by numerical analyses to verify the validation of Levenberg-Marquardt algorithm adopted as training method in this paper. Many parameter studies fur the flat slab structural system show dominant vehicle load effects at the center positive moments in both column and middle strips, like the beam-girder parking structural system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.2
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• pp.115-124
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• 2003

In this paper, the effects of vehicle loads on flat slab system are investigated on the basis of the previous studies for beam-gilder parking structural system. The influence surfaces of flat slab for a typical design section are constructed lot the purpose of obtaining maximum member forces under vehicle loads. In addition, the equivalent vehicle load factors for flat slab parking structures are suggested using artificial neural network. The network responses we compared with the results obtained by numerical analyses to verify the validation of Levenberg-Marquardt algorithm adopted as training method in this Paper. Many parameter studies for the flat slab structural system show dominant vehicle load effects at the center positive moments in both column and middle strips, like the beam-girder parking structural system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.143-150
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• 2001

In this paper, the effects of vehicle loads on flat slab system are investigated based on the previous studies on beam-girder parking structural system. The influence surfaces of flat slab for typical design section are determined for the purpose of obtaining member forces under vehicle loads. In addition, the equivalent vehicle load factors for flat slab parking structures are suggested using neural network. It has been found that vehicle load effects of flat slab system are dominant for the center positive moment in both column and middle strip, as like beam-girder parking structural system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.230-237
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• 2000

The purpose of this study is to evaluate the dynamic behavior of highway bridge due to moving vehicle load, considering the effect of laminated rubber bearing. Dynamic behaviors of bridge considering the effect of bearings are studied with 3-dimensional bridge and vehicle models. To analyze the effect of bearings on the dynamic behaviors of superstructures of bridges, laminated rubber bearing is modeled as 3-dimensional frame element with equivalent stiffness and damping, and the models are included in the bridge analysis model. The results from the analytical models with laminated rubber bearing show a significant effects on dynamic responses and more complex vibration characteristics compared with the results from the bridge with pot bearings. Generally, larger dynamic amplification factors are obtained in the case of laminated rubber bearing, which is mainly due to the smaller torsional stiffness of the bridge with laminated rubber bearing. It can be recommended that were careful consideration on the vibration of bridges and dynamic load allowance in design are needed when adopting laminated rubber bearing.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.199-210
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• 2011

The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.

• International Journal of Automotive Technology
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• v.7 no.6
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• pp.757-762
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• 2006

Reliability of automotive parts has been one of the most interesting fields in the automotive industry. Especially, a small DC motor was issued because of the increasing adoption for passengers' safety and convenience. For several years, small DC motors have been studied and some problems of a life test method were found out. The field condition was not considered enough in the old life test method. It also needed a lot of test time. For precise life estimation and accelerated life test, new life test procedure was developed based on measured field condition. The vibration condition on vehicle and latent force on fan motor shaft were measured and correlated with each other. We converted the acceleration data into the load data and calculated the equivalent load from integrated value. We found the relationship which can be used for accelerated life test without changing the severity by using different loading factors.

• Journal of Korean Society of Steel Construction
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• v.25 no.4
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• pp.335-346
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• 2013

AASHTO LRFD and Korean Bridge Design Code (Limit State Design) specify to consider Truck and Lane load simultaneously determined from reliability-based live load model, and impact shall be applied to the truck load while it shall not be applied to the lane load. In this paper, vehicle-bridge interaction analysis under moving truck and lane loads were performed to estimate impact factor of the cables and girders for the selected multi-cable-stayed composite bridges with 230m, 400m and 540m main span. A 6-d.o.f. vehicle was used for truck load and a series of single-axle vehicles was applied to simulate equivalent lane load. The effect of damping ratio on the impact factor was estimated and then the essential parameters to impact factor, i.e., road surface roughness and vehicle speed were considered. The road surface roughness was randomly generated based on ISO 8608 and it was applied to the truck load only in the vehicle-bridge interaction analysis. The impact factors evaluated from dynamic interaction analysis were also compared with those by the influence line method that is currently used in design practice to estimate impact factor in cable-stayed bridge.