• Structural Engineering and Mechanics
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• v.14 no.2
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• pp.171-190
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• 2002

Two cases of design are performed for the hyperbolic paraboloid saddle shell (Lin-Scordelis saddle shell) and the hyperbolic cooling tower (Grand Gulf cooling tower) to check the design strength against a consistent design load, therefore to verify the adequacy of the design algorithm. An iterative numerical computational algorithm is developed for combined membrane and flexural forces, which is based on equilibrium consideration for the limit state of reinforcement and cracked concrete. The design algorithm is implemented in a finite element analysis computer program developed by Mahmoud and Gupta. The amount of reinforcement is then determined at the center of each element by an elastic finite element analysis with the design ultimate load. Based on ultimate nonlinear analyses performed with designed saddle shell, the analytically calculated ultimate load exceeded the design ultimate load from 7% to 34% for analyses with various magnitude of tension stiffening. For the cooling tower problem the calculated ultimate load exceeded the design ultimate load from 26% to 63% with similar types of analyses. Since the effective tension stiffening would vary over the life of the shells due to environmental factors, a degree of uncertainty seems inevitable in calculating the actual failure load by means of numerical analysis. Even though the ultimate loads are strongly dependent on the tensile properties of concrete, the calculated ultimate loads are higher than the design ultimate loads for both design cases. For the cases designed, the design algorithm gives a lower bound on the design ultimate load with respect to the lower bound theorem. This shows the adequacy of the design algorithm developed, at least for the shells studied. The presented design algorithm for the combined membrane and flexural forces can be evolved as a general design method for reinforced concrete plates and shells through further studies involving the performance of multiple designs and the analyses of differing shell configurations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.212-221
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• 2022

In this paper, the evaluation procedure applying the limit state design method is studied to be consistent with the newly issued bridge design code in Korea. The live load factor for evaluation is proposed by calibrating for the target reliability index through reliability analysis. Using the actual bridge information collected for the representative bridge types in Korea, the load effects of the design live loads for the previous and current design codes are calculated and compared. The live load factor is calibrated through reliability analysis using the minimum required strength which equals to the load effect obtained for the example bridge. Bridge evaluation is performed by applying the live load factors for the evaluation level as well as design level. The load rating result is generally increased by applying the limit state design method compared to the previous design method and applying the proposed load factor for lowered target reliability index further increased the rating result.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.26-32
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• 2000

Design load calculations which depend on the thermal characteristics of the building structure such as the wall, roof, and fenestration provide the basic data for selecting an HVAC system and its equipment. Most of domestic multi-family houses include a high thermal storage layer like massive concrete structure and a floor heating structure. This study is to compare the results of the design heating load between steady state and unsteady state calculation in order to comprehend the thermal storage effect in multi-family houses. The design heating load under the steady state calculation is estimated from 5.4% to 7.8% larger than that under the unsteady state in the typical floor of a multi-family house model. The design heating load considered the safety factors like a orientation and location factor also is 21.4% to 26.5% larger than that by the unsteady state calculation. So, the safety factors for use of the practicing engineer are analyzed as the main factor of a heating plant oversizing.

• Earthquakes and Structures
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• v.25 no.5
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• pp.307-323
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• 2023

This study compares two prominent design provisions, National Design Specification (NDS) and Eurocode 5, on load-carrying capacity calculations and failure analysis for mortise-tenon joints. Design procedures of double-shear connection from both provisions were used to calculate load-carrying capacity of mortise-tenon joints with eight different bolt sizes. From this calculation, the result was validated using finite element analysis and failure criteria models. Although both provisions share similar failure modes, their distinct calculation methods significantly influence the design load-carrying capacity values. Notably, Eurocode 5 predicts a 6% higher design load-carrying capacity for mortise-tenon joints with varying bolt diameters under horizontal loads and 14% higher under vertical loads compared to NDS. However, the results from failure criteria models indicate that NDS closely aligns with the actual load-carrying capacity. This indicates that Eurocode 5 presents a less conservative design and potentially requires fewer fasteners in the final timber connection design. This evaluation initiates the potential for the development of a wider range of timber connections, including mortise-tenon joints with wooden pegs.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.29-40
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• 2018

Strength design wind loads for the wind resistance design of structures shall be evaluated by the product of wind loads calculated based on the basic wind speed with 100 years return period and the wind load factor 1.3 specified in the provisions of load combinations in Korean Building Code (KBC) 2016. It may be sure that the wind load factor 1.3 in KBC(2016) had not been determined by probabilistic method or empirical method using meteorological wind speed data in Korea. In this paper, wind load factors were evaluated by probabilistic method and empirical method. The annual maximum 10 minutes mean wind speed data at 69 meteorological stations during past 40 years from 1973 to 2012 were selected for this evaluation. From the comparison of the results of those two method, it can be found that the mean values of wind load factors calculated both probability based method and empirical based method were similar at all meteorological stations. When target level of reliability index is set up 2.5, the mean value of wind load factors for all regions should be presented about 1.35. When target level of reliability index is set up 3.0, wind load factor should be presented about 1.46. By using the relationship between importance factor(conversion factor for return period) and wind load factor, the return periods for strength design were estimated and expected wind speeds of all regions accounting for strength design were proposed. It can be found that return period to estimate wind loads for strength design should be 500 years and 800 years in according to target level of reliability index 2.5 and 3.0, respectively. The 500 years basic wind speed map for strength design was suggested and it can be used with a wind load factor 1.0.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.5
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• pp.326-333
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• 2009

Design life-time of a wind turbine is required to be at least 20 years. In the meantime, the wind turbine will experience a lot of load cases such as extreme loads and fatigue loads which will include several typhoons per year and extreme gusts with 50 years recurrence period as well as endless turbulence flow. Therefore, IEC61400-1 specifies design load cases to be considered in the wind turbine design and requires the wind turbine to withstand the load cases in various operational situations. This paper investigates the ultimate loads which the wind turbine will experience for 20 years and their characteristics based on the IEC61400-1 using an aero-elastic software, GH-Bladed. And the performance characteristics of a wind turbine such as electrical power generation and annual energy yield are also investigated.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1043-1050
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• 2010

This paper examined the probabilistic load analysis for the tailplane during pitching maneuvering in the conceptual aircraft design phase. The flight load analysis based on the probabilistic distribution of design variables are compared with the results of the deterministic analysis. Two forms of variable distribution are used in this paper. One is standard normal distribution, the other distribution is calculated from the results of short-period longitudinal equation of aircraft motion. The influence of the distribution parameter on the probabilistic load analysis was investigated and the significant design variables that have an impact on the mean and variance of probabilistic load were identified. The comparison indicates that probabilistic load analysis provides more reliable probabilistic load distribution for the structural design than the traditional deterministic analysis.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2880-2885
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• 2008

Design lifttime of a wind turbine is required to be at least 20 years. In the meantime, the wind turbine will experience a lot of load cases such as extreme loads and fatigue loads which will include several typhoons per year and extreme gusts with 50 years recurrence period as well as endless turbulence flow. Therefore, IEC61400-1 specifies design load cases to be considered in the wind turbine design and requires the wind turbine to withstand the load cases in various operational situations. This paper investigates the ultimate loads which the wind turbine will experience for 20 years and their characteristics based on the IEC61400-1 using an aero-elastic software, GH-Blade. And the performance characteristics of a wind turbine such as electrical power generation and annual energy yield are also investigated.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.6
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• pp.373-380
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• 2020

We have developed the hybrid prototype load cell structures. These developed load cell structures may increase the reliability of the load sensing by deriving the load values through the double sensing method through the vertical maximum deflection and bending stress of the simple beams. For this purpose, the structure design was performed so that the load value, the deflection and stress value could be output to the same value through the optimal structure design. The structurally designed dimensions reaffirmed the accuracy of the design through the structural analysis program and the matching of the load value and the deflection value. Based on the designed structural dimension, the prototype form was constructed through laser cutting and production using hot rolled steel materials. The developed prototype load cell structure can be used as good educational material in various subjects such as material mechanics, steel structure design, measurement engineering, and mechatronics engineering. It is also believed that the measurement system ideas can inform the occurrence of errors in the event of a problem, and if a major accident caused by a sensing error is predicted, it will show good utilization to prevent accidents.

• Tribology and Lubricants
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• v.18 no.3
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• pp.181-186
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• 2002

A numerical analysis is undertaken to show the influence of bearing design parameters on the load capacity of air lubricated spiral grooved thrust bearing. The governing equation derived from the mass balance is solved by the finite difference method. Optimal values for various design parameters are obtained to maximize the load capacity. The design parameters are the groove angle, the groove width ratio, the groove height ratio, and the seal ratio.