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Torque control method and turn of nut method are specified as clamping method of high strength bolts in the steel construction specifications. Quality control of torque coefficient is essential activity because torque control method, which is presently adopted as clamping method in domestic construction sites, is affected by variation of torque coefficient. The clamping of torque shear bolt is based on KS B 2819. It was misunderstood that the tension force of the TS bolt was induced generally at the break of pin-tail specified. However, the clamping forces on slip critical connections do not often meet the intended tension, as it considerably varies due to torque coefficient dependent on the environmental factors and temperature variables despite the break of the pin tail.This study was focused to evaluate the effect of environmental factors and errors of installing bolts during tightening high strength bolts. The environmental parameters were composed of 'wet' condition, 'rust' condition, 'only exposure to air' condition. And the manufacture of trial product was planned to identify the induced force into the bolts. The algorithm for a trial product was composed of the relation between electricity energy taken from torque shear wrench and tension force from hydraulic tension meter.

The initial clamping forces of high strength bolts subjected to different faying surface conditions drop within 500 hours regardless of loading, any other external force or loosening of the nut. This study develops a mathematical model for relaxation confined to creep on a coated faying surface after initial clamping. The quantitative model for estimating relaxation was derived from a regression analysis for the relation between the creep strain of the coated surface and the elapsed time for 744 hours. This study establishes an expected model for estimating the relaxation of bolted joints with diverse coated surfaces. The candidate bolts are dacro-coated tension control bolts, ASTM A490 bolt, and plain tension control bolts. The test parameters were coating thickness, species of coating. As for 96, 128, 168, and 226 μm thick inorganic zinc, when the coating thickness was increased, relaxation after the initial clamping rose to a much higher range from 10% to 18% due to creep of the coating. The amount of relaxation up to 7 days exceeded 85% of the entire relaxation. From this result, the equation for creep strain can be derived from a statistical regression analysis. Based on the acquired creep behavior, it is expected that the clamping force reflecting relaxation after the elapse of constant time can be calculated from the initial clamping force. The manufacturer's recommendation of inorganic zinc on faying surface as 75 μm, appears to be reasonable.

An epoxy coating applied to the concrete surface of a containment building deteriorates in hazardous environments such as those containing radiation, heat, and moisture. Unlike metals, the epoxy coating on a concrete liner absorbs and discharges moisture during the degradations process, so it has a different density and volume during service. In this study, acoustic impedance was adopted for characterizing the degradation of a glass-reinforced epoxy coating using the acoustic reflection coefficient (reflectance) on a rough epoxy coating. For estimating the acoustic reflectance on a wavy epoxy coating surface, a probabilistic model was developed to represent the multiple irregular reflections of the acoustic wave from the wavy surface on the basis of the simulated annealing technique. A number of epoxy-coated concrete specimens were prepared and exposed to accelerated aging conditions to induce an artificial aging degradation in them. The acoustic impedance of the degraded epoxy coating was estimated successfully by minimizing the error between a waveform calculated from the mathematical model and a waveform measured from the surface of the rough coating.

This project is mainly related to evaluation of total energy consumption of low energy house, the exterior envelope of which was wholly composed of structural insulated panels(SIP). The U-value of applied SIP was in the range of 0.189 to 0.269W/ K and the U-value of pair glass from 0.78 to 1.298W/ K was applied for window ㎡· ㎡· dependent to its function respectively. For comparison of total energy performance, the energy simulation for pilot house was performed to compare with the control house having insulation criteria of Korean building regulation in 2009. Based on simulation of dynamic energy performance, the pilot house saved 48.3% of annual energy consumption while the control house in 2009 consumed as 85.7GJ/y. In case of heating, the result showed that the energy saving ratio amounted to 76.7%. For CO emission, the pilot house diminished approximately 35.4% from 6,208.4kgCO to ₂ ₂

There are few technical documents regulated structural performance and engineering criteria in domestic market for Structural insulated panels in Korea. This paper was focused to identify fundamental performance under monotonic loading and cyclic loading for SIPs in shear wall application. Load-displacement responses of total twelve test specimens were recorded based on shear stiffness, strength, ultimate load and displacement. Finally energy dissipation of each specimen was analyzed respectively. Monotonic test results showed that ultimate load was 44.3 kN, allowable shear load was 6.1 kN/m, shear stiffness was 1.2 MN/m, and ductility ratio was 3.6. Cyclic test was conducted by two kinds of specimens: single panel and double panels. Cyclic loading results, which were equivalent to monotonic loading results, showed that ultimate load was 45.4 kN, allowable shear load was 6.3 kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times as that for single panel. Based on results of structural performance test, it was recommended that the allowable shear load for panels should be 6.1 kN/m at least.

Professor, The University of Seoul, Department of Architectural EngineeringAbstract:Structural insulated panels, structurally performed panels consisting of a plastic insulation bonded between twostructural panel facings, are one of emerging products with a viewpoint of its energy and construction efficiencies.These components are applicable to fabricated wood structures. In Korea, there are few technical documents regulatedstructural performance and engineering criteria in domestic market. This study was conducted to identify fundamentalperformance of both monotonic load and quasi static cyclic load for SIPs in shear wall application. Static test resultsshowed that maximum load was 44.3kN, allowable shear load was 6.1kN/m, shear stiffness was 1.23 MN/m, andductility ratio was 3.6. Cyclic test was conducted by two kinds of specimens : single panel and double panels. Cyclictest results, which were equivalent to static test results, showed that maximum load was 45.42kN, allowable shearload was 6.3kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times asthat for single panel. From performance of structural tests, it was recommended that the allowable shear load for panelswas at least 6.1kN/m.K

Structure Insulated Panel (SIP) is an wooden structure material with which structure and insulation functions are satisfied. Hence, it would be a cost-effective model to implement low energy house which has higher insulation and structure performance and which the wall thickness is able to be reduced. In this study, performance of thermal insulation and fire resistance were evaluated in order to verify applicability to low energy house. Fire resistance test is performed on vertical load bearing members for partitions, and the test results satisfy one hour of fire resistance condition according to KS F 2257. The members include two layers of fireproof gypsum board with thicknesses of 12.5mm attached to SIP. Thermal insulation performance is satisfied with the 2012 standard (0.225W/㎡·K). As the performance of resistance and thermal insulation are satisfied, SIP is expected to be applied to low energy building materials. In the future, the structural safety will be confirmed by structural performance and seismic performance test and the guidelines for distribution will be drawn up.

Structural insulated panels, which are structurally performed panels consisting of a plastic insulation bonded between two structural panel facings are one of emerging products with a viewpoint of its energy and construction efficiencies. These components are applicable to fabricated wood structures. By now, there are few technical documents regulated structural performance and engineering criteria in domestic market. This study was conducted to suggest fundamental reports such as racking resistance, axial capacity, transverse load capacity, and lintel load capacity for SIPs. Test results showed that maximum load was 44.3kN, allowable load was 14.7kN for racking resistance, and that maximum load was 137.6kN, allowable load was 37.4kN/m for axial compression capacity. For transverse load capacity, test results showed of maximum load, of allowable load. For lintel load capacity for SIPs dependent to lengths, allowable loads were 20.4kN for 600mm long lintel, 23.9kN for 1,200mm long lintel, 19.3kN for 1,800mm long lintel, and 2,400mm long lintel had 14.1kN of allowable load. In the near future, when the allowable load for wall application is established, SIPs is considered to substitute the existent post-and-lintel construction to bearing wall structure.

Clamping force of a high strength bolt is reduced by a certain period of time after the initial set-up. In case of special treatments on faying surfaces such as protective coating, clamping force is relaxed more severely. Tests for slip critical joints subject to various faying surface parameters were conducted. Five different surface treatments were tested including mill scale surface, blast surface, rust surface and coated surfaces. Each specimen was composed of F10T M20 of high strength bolts and steel plates. Based on the result of slip coefficient test, blast treatment surface showed 0.59, rust treatment surface showed 0.54 and inorganic zinc treatment surface exhibited 0.44. Clean mill treatment surface and red lead paint treatment surface were 0.23, 0.21 respectively. It is identified that the slip coefficient in Korean structural design guide should be determined for various surface conditions. Subsequently from long term relaxation test of ASTM A 490 high strength bolts, relaxation of no-coated surfaces such as blast, clean mill, rust treatment, the loss of initial clamping load was 10.5%, 13.6% and 7.9% for 1,000 hours, while the loss of initial clamping force was reached as 15.0%, 18.7% more than the required redundancy 10% in case of inorganic zinc and red lead painted treatment. It is required that the limit of relaxation on coated faying surface should be established separately for various surfaces.

The initial clamping forces of high strength bolts depending on different faying surface conditions drop within 1,000 hours regardless of loading, any other external force or loosening of the nut. This study is focused on an expectation model for relaxation of high strength bolt, which is confined to creep on coated faying surfaces after initial clamping. The range of this experiment is limited to estimate the relaxation of bolted joints coated by inorganic zinc primer. The candidate bolts were dacro-coated tension control bolts. The parameters of coated thickness for the faying surface were 96, 168,and respectively. From experiments, it exhibited that the logarithmic function for creep strain was derived due to the parameter of coating thickness. By using the creep strain, subsequently the quantitative model for estimating long term relaxation of high strength bolt can be taken with the elapsed time. The experimental results showed that the relaxation after the initial clamping of high strength bolt rose to a much higher range from 10% to 18% due to creep of the coating as the coating thickness was increased. This study showed that the clamping force reflecting relaxation after the elapse of constant time can be calculated from the initial clamping force of high strength bolt.

In this paper, some ideas are proposed to establish the infrastructure of all-electric houses which are able to reduce primary energy consumption and CO2 emission by adopting heat pump systems and induction heating cookers excluding the use of fossil fuel energy. This electrification concept is based on the consumption of only one type of energy which means electricity as secondary energy and the conventional fossil fuel energy is just consumed to generate electricity as primary energy. All-electric house is laid on the extension of the hydrogen economy in a long-term viewpoint so that the effectiveness of this new conceptual house is estimated analyzing the reduction of CO2 emission. In this analysis, the balance of electricity supply and demand is considered including the construction of new power plants by renewable energy such as nuclear, IGCC and fuel cell because decarbonization is an essential element of hydrogen technology and economy and this action is accomplished in both supply and demand side of electricity. The results are able to contribute to develop various useful hydrogen policies and strategies and some detail researches are required previously to make the best application of this new conceptual house.

Recently, all-electric house technology became one of the green growth technologies and is integrated with various areas such as electricity, machinery, architecture, material, and etc. Fossil fuel energy is used for heating and hot water supply in the conventional houses but electricity is adopted in the new conceptual houses to maximize advantages of electricity such as amenity, safety, cleanness, and so on. In this paper, an economic analysis is carried out when LED lightings are adopted using the California Standard Practice Test which has been used to estimate the effects of existing DSM (Demand Side Management) programs. The results are able to contribute to the diffusion of all-electric houses and the establishment of basic data and planning for DSM policies.

Recently, low energy houses have become an essential issue globally and various subsidy programs are ongoing to penetrate. All-electric houses which are another type of low energy houses or zero carbon houses are being developed. These houses consider new & renewable energy and demand side management programs in the construction and the diffusion process because these programs are essential policies to use energy resources reasonably. This paper shows a simulation methodology to control home appliances in all-electric houses considering the electricity consumption pattern of residents. The simulation is a first step to estimate energy saving of the house in a practical manner.

The oversized and slotted holes are frequently required for the built-up in construction sites. The foreign provisions specify the reduction of the slip load subjected to the size of bolt holes and the direction of load. There are no domestic building codes and researches on the bolt holes. Therefore, it is necessary to evaluate a change of joint strength quantitatively according to the bolt-hole size and surface condition by means of experiment. This study was conducted to evaluate the slip load subjected to the size of bolt holes, and measured on a change of clamping force of high strength bolts during 168 and 800 hours to analyze the trend of relaxation after fastening bolts. Torque shear bolts defined on KS B 2819 was used for the specimen. Test results exhibit that the variation on the slip load of the others was below 10% by contrast with the standard hole and the highest rate of relaxation was 2.66% of the initial clamping force at the case of the long-slotted hole of 2.5D.

Recently, safety diagnosis of the existing structures has been emerged as important issue. In particular, systematical and precise safety diagnostics for steel structures for power substation, have been required. Steel structures for power substation are under the periodical impact loads from operations of gas insulated switchgear. These loading condition accelerates damage and aging of structure. The objective of this research is to evaluate damage of structure under periodical impact loads. To evaluate the integrity of structures as organizing mathematical models including the dynamic characteristics of structures, Frequency Domain Decomposition method was choiced and an algorism was proposed. For verifying this methods and algorism, a mathematical model is composed of the development of a variety of reverse analysis and a signal processing technology reflecting physical damage of structures. A series of analysis and test results indicatge that proposed method has a confidence for applying a filed test. Therefore, it is expected to be able to take advantage of system identification to detect damage for the maintenance and management of steel structures under periodical impact loads such as power substation.

The clamping force of a high-strength bolt reduces within a certain time period after the initial clamping force. When special treatments are used on a faying surface, the clamping force is relaxed severely. Tests were conducted for slip critical joints subjected to various faying surface parameters. Relaxation occurred for slip resistant joints with an uncoated surface that had been shot-blasted, cleaned, milled or rusted. It was observed that the initial clamping force dropped from 6.2% to 8.0% after 744 hours. For joints with a 5 mil thick zinc coating, the clamping force of the bolts decreased by 8.37%, and in the case of 4.9 mil thick red lead painted treatment, the relaxation ratio was 24.6%. The standard deviation of the slip coefficients between the time immediately after tightening and 1,000 hours after tightening was 0.223. It is particularly noteworthy that, for red lead painted treatment, the slip coefficient dropped from 2.5 times to 2.8 times when compared with the slip coefficient before relaxation. Joints with inorganic zinc should not have thickness exceeding 5 mils, and joints with a red lead painted surface should not be allowed regardless of the thickness of coating.

A slip critical joint has various values to adopt the proper slip coefficient in various conditions of faying surfaces in the following codes: AISC, AIJ and Eurocode 3. However, the Korean Building Code still regulates the unique slip coefficient, 0.45, regardless of the diverse faying conditions. In this study, the slip resistance test, including five kinds of surface treatments were conducted to obtain the proper slip coefficients available to steel plate KS SM490A. The faying surfaces were comprised of a clean mill, rust, red lead paint, zinc primer, and shot blast treatment. The candidates for high strength bolts were torque-shear bolts, torque-shear bolts with zinc coating, and ASTM A490 bolts. Based on the test results, the specimens with a shot blasted surface and rusted surface exhibited , 0.61, and 0.5, respectively. It is recommended that the specimens with zinc primer exhibit . The clean mill treated surface had prominently lower values, 0.27. For red lead painted treatment, the thickness of the coating affects the determinant of slip coefficient, so it is necessary to establish a minimum of 0.2, with a coating thickness of 65 . During 1,000 hours of relaxation, the uncoated surfaces exhibited the loss of clamping force behind 3%, while the coated surfaces within a certain limited thickness exhibited the loss of clamping within a range of 4.71% and 8.37%.

The torque control method is mainly used as a clamping method for high-strength bolts in Korea and Japan. However, the torque coefficient affects the tension that is required during the process of tightening by torque. This makes it difficult to assume the direct tension induced into the bolt. The determinant factor that affects the clamping force is the ambient temperature, as indicated by the Korean standard B 2819. This study was planned to assess the expected clamping force of two types of high-strength bolts considering a temperature range of-10 to 50°C. Based on laboratory data subjected to temperature parameters, equations to estimate the clamping force were extracted by regression analysis.

A slip critical connection has various values to adopt the proper slip coefficient in various conditions of faying surfaces in AISC, AIJ and Eurocode3. The Korean Building Code regulates the unique slip coefficient, from 0.45 to 0.5 without consideration of the diverse faying conditions in 2009. In this study, the slip resistance test, including five kinds of surface treatments were conducted to obtain the proper slip coefficients available to steel plate KS SM490A. The slip coefficient of specimens over zinc primer thickness of 128 μm exhibit was 0.42. The clean mill treated surface had prominently lower values as slip coefficient, 0.27. For red lead painted treatment, it is suggested to setup a minimum slip coefficient, 0.21, below a coating thickness of 65 μm. The slip coefficient of one faced lap connection was higher 1.4 times than the slip coefficient of two faced lap connection.