• International Journal of Highway Engineering
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• v.14 no.2
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• pp.29-36
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• 2012

In this study, frequently passing vehicles with two, three, four, and five axles were chosen through traffic volume analysis in Kyung-In Expressway in order to analyze how the road roughness and vehicle speed affect on the dynamic loads for roads in various vehicle classes. Dynamic loads according to chosen vehicles are estimated by TruckSim program. Dynamic load amplification factor is ratio between dynamic and static loads, and it is also determined for each vehicle classes. From the result of dynamic loads estimated by the dynamic load amplification factor, it is shown that for three-axles vehicle, when IRI is 3.5 and vehicle speed is 100km/hr, asphalt pavements receive additional 36% of static loads in maximum. The analysis of the amplification factor according to each vehicle classes also indicates that the amplification factor increases as the distance between the axles becomes smaller and each axle receives more loads.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.675-684
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• 2022

The conventional single-degree-of-freedom (SDOF) system is appropriate for dynamic response analysis of paneltype structures without an opening. However, the typical building structures usually have four-sided fixed walls having an opening. Therefore, it may induce a considerable error when dynamic responses are estimated based on the conventional SDOF system, since the SDOF system cannot consider the effect of an opening during the SDOF analysis. For this reason, this study proposes a new SDOF system to consider the effect of an opening by adjusting its load-mass factor. The load-mass factor can be modified based on the assumption that the behaviors of the four-sided fixed wall with an opening is very similar to the behaviors of the same size wall without an opening, when the uniformly distributed blast loaded area is identical. In order to confirm a feasibility of the proposed SDOF system, a series of numerical simulations were carried out for the four-sided fixed reinforced concrete (RC) wall under a blast load. The dynamic responses estimated from the proposed SDOF system and the conventional SDOF system were compared with the dynamic responses evaluated from the finite element (FE) analysis. Especially, for the maximum dynamic responses except for 50% opening case, the proposed SDOF system had about 1.1% to 25.7% normalized errors while the conventional SDOF system had about 4.1% to 49.1% normalized errors.

• Journal of Korean Association for Spatial Structures
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• v.5 no.1 s.15
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• pp.81-89
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• 2005

Walking loads are influenced by various parameters so that they need to be measured considering such parameters. Walking frequency(rate) is experimentally investigated as the most important parameter in determining the walking load expressed with dynamic load factor. This study focuses on the derivation of continuous walking load-time functions at any walking frequency ranging from 1.30Hz to 2.70Hz. Experiments were conducted to obtain time-histories of walking loads at the increment of 0.1Hz, which are decomposed into harmonic loads by the Fourier transformation. The polynomial load-time functions are proposed representing the relationship between harmonic coefficients and walking frequencies, thereby easily formulating walking load-time histories for dynamic load factor with various walking frequencies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.70-76
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• 2013

The objective of the paper is to present the results of analytical and experimental studies dealing with dynamic load for continuous steel girder bridges due to normal truck traffic. Various bridge design codes specify dynamic load factor (defined as a fraction of static portion of live load) for short span structures at the level of about 0.3. However, there are not definite values specified for continuous brigdes. Therefore, it is an usual practice to use the code specified dynamic load factors for simple span bridges to continuous bridges without clear background. The field measurement results indicate that the actual dynamic load factors are less than 0.2 for a single truck, and less than 0.05 for two trucks side-by-side, regardless of positive and negative moment region.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.784-791
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• 2006

This paper presents the test results to evaluate the healthiness of the ballast in subway. The test includes the dynamic load test in servicing Line the screen classification test of aggregates and the wear test. From the results, the aspect and the property of the ballast are evaluated. The dynamic load tests explain the relationship between the deterioration of the ballast and the fluctuation of loads. The assessment of impact factor based on the field test results in a good property of test blocks is proposed.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.484-493
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• 2006

This paper is presented the test results to evaluate the healthiness of the ballast in subway. The test includes the dynamic load test in servicing Line the screen classification test of aggregates and the wear test. From the results, the aspect and the property of the ballast are evaluated. The dynamic load tests the relationship between the deterioration of the ballast and the fluctuation of loads. The assesexplain sment of impact factor based on the field test results in a good property of test blocks is proposed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.313-330
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• 1993

The propagating crack problems under dynamic plane mode in orthotropic material is studied in this paper. To analyze the dynamic fracture problems in orthortropic material, it is important to know the dynamic stress components and dynamic displacement components around the crack tip. Therefore the dynamic stress components of dynamic stress field and dynamic displacement components of dynamic displacement field in the crack tip of orthotropic material under the dynamic load and the steady state in crack propagation were derived. When the crack propagation speed approachs to zero, the dynamic stress component and dynamic displacement components derived in this study are identical to the those of static state. In addition, the relationships between dynamic stress intensity factor and dynamic energy release rate are determinded by using the concept of crack closure closure energy with the dynamic stresses and represented according to physical properties of the orthotrophic material and crack speeds. The faster the crack velocity, the greater the stress value of stress components in crack tip. The stress value of the stress component of crack tip is greater when fiber direction coincides with the crack propagation than when fider direction is normal to the crack propagation.

• Bulletin of the Society of Naval Architects of Korea
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• v.15 no.3
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• pp.1-7
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• 1978

The dynamic pressures on the bottom of high speed small crafts are studied. Using the dynamic load factor the dynamic pressure can be replaced by equivalent static pressure. Assuming that (1) the system is undamped with a single degree of freedom and (2) the load is applied triangularly, we obtained the max, value of the dynamic load factor of 1.455. We believe that this method could provide a guide to the designer who has no data on the craft in the preliminary structural design stage.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.111-118
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• 1996

Dynamic load models which show the practical behavior of truss bridge subjected to moving train load are presented. Three basically approaches are available for evaluating structural response to dynamic effects : moving force, moving mass, and influence moving force and mass. Simple warren truss bridge model is selected in this research, and idealized lumped mass system, modelled as a planar structure. In the process of dynamic analysis, the uncoupled equation of motion is derived from simultaneous equation of the motion of truss bridge and moving train load. The solution of the uncoupled equations of motion is solved by Newmark-$\beta$ method. The results show that dynamic response of moving mass and static analysis considering the impact factor specified in the present railway bridge code was nearly the same. Generally, the dynamic response of moving force is somewhat greater than that of moving mass. The dynamic load models which are presented by this study are obtained relatively adequate load model when apply to a truss bridge.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.319-326
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• 2000

It is investigated character of the dynamic behavior at over excavation zone of roadbed using crushed stone instead of lean concrete. It is considered that behavior of roadbed using PENTAGON-3D and Baber's equation. Typical load of sine wave type using impact factor is compared to moving load system to examine relationship in using PENTAGON-3D case. Variations of this paper are material properties of roadbed, train velocity, subgrade bearing capacity. Using variations, safety of roadbed is estimated by dynamic behavior character.