• Journal of Korean Society of Steel Construction
• /
• v.20 no.6
• /
• pp.701-709
• /
• 2008

Owing to the decreased work term and the convenience of construction work in Korea, the steel deck plate system has been widely used in the construction field. Most of all, due to its good stiffness and economic consideration, the steel-wire-integrated deck plate system (or truss deck plate system) has become very popular in recent years. But although it has many advantages, the truss deck plate system has a critical defect: it gets rusty in the welding joints between the lattice steel wire and the deck plate, resulting in the cracking of such welding joints and water leakage. To address these problems, a new type of truss deck plate system, which need not be welded and does not rust, was proposed herein: the TOX deck plate system. In this study, tests were conducted on 15 specimens to evaluate the structural safety of the proposed deck plate system during the construction stage. The test parameters were as follows: the depth of the slab the length of the span the diameters of the top, bottom, and lattice steel wire and the material properties of the zinc-coated steel sheets. The test results show that the TOX deck plate system can guarantee structural safety owing to its deflection and strength.

• Journal of Korean Society of Steel Construction
• /
• v.21 no.3
• /
• pp.221-232
• /
• 2009

The load distribution factor (LDF) values of simplified composite H beam panel bridges (SCHPBs) that were subjected to one lane and two lane loads were investigated using three dimensional finite element analyses with the computer program ABAQUS (2007). This study considered some design parameters such as the slab thickness, the steel plate thickness, the span length, and the continuity of the SCHPBs in the development of new LDFs. The distribution values that were obtained from these analyses were compared with those from the AASHTO Standard, LRFD, and the equations presented by Tarhini and Frederick, Huo et al., Back and Shin, and Cai. The AASHTO Standard distribution factors for SCHPBs were found to be very conservative. Sometimes, the distribution values from the finite element analyses for interior girders were similar to the results of the AASHTO LRFD, whereas the values for exterior girders were conservative in most cases. The new distribution values that were presented in this study produced LDFs that are more conservative than those from the finite element method. For the simple application of the design to SCHPBs, bridge engineers can use 0.42 for the interior girder and 0.32 for the exterior girder. The proposed values improve the current design procedure for the LDF problem and increase SCHPB design efficiency.

• Journal of Korea Water Resources Association
• /
• v.31 no.4
• /
• pp.397-406
• /
• 1998

The Pyokkolche Reservoir was constructed as a major public project of the ancient agricultural society, 1600 years ago. From a hydraulic point of view, it is considered to have been carried out with a distinguished technology. It should be in particular noticed that for a consecutive banking the main stream was diverted and drained to the Yonpo stream and the dam with same sea levels on its top along the whole length was built in a nearly straight line in spite of the different sea levels between both ends on the bottom. These suggest that the carrying out artifice and surveying technigue of those days were considerably excellent. However, the insufficient plan and design at the time of the construction, the temporary management and the repeated repair works in the later ages caused the Pyokkolche to lose its function. The Changsaenggeo and Kyungjanggeo gate sites being the facilities for sluices composed of a simple span and a vertical lift hand-operated sing a pully. The advantage of the geographical characteristics at both ends of the main dam was scientifically taken to these sites which also functioned as a spillway against a flood. The gate site of Suyogeo must have been located in an entrance to Suwolri, the northern end of the Pyokkolche and Yutonggeo is presumed to have been located on the right of Sangsori, the southern end of the Pyokklche. Keywords : Pyokkolche Reservoir, construction technology, gate site location.

• Journal of the Korean Society for Railway
• /
• v.20 no.2
• /
• pp.241-247
• /
• 2017

Railway bridges with continuously welded rail have a limitation of span length due to track-bridge interaction. In order to overcome this, a sliding slab track system has been developed that comprises with a low-frictional sliding layer between the bridge deck and the track slab to isolate the longitudinal behavior between the bridge and the track. In this study, a real scale track system is prepared to experimentally evaluate the longitudinal frictional behavior. Applied loading rates were 0.2, 1.0, 5.0 and 10mm/min; vertical mass on the track are track slab only, 5,000 and 10,000kg added mass, respectively. Test results showed that the resulting frictional coefficients varied from 0.22 to 0.33. In addition, 10,000 cycle loadings were applied to simulate repetitive sliding to represent 30 years of service life. The frictional coefficient increase was measured and found to be 7% of that of the initial loading stage, which means that the sliding layer is adequate to provide low-frictional behavior for the sliding slab track system. Effects of changes of the frictional coefficient of the sliding layer were analyzed by rail-structure interaction analysis.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.24 no.4
• /
• pp.10-17
• /
• 2020

The recent earthquake in Korea caused large and small damages to many school building. School building is an important building that is used as a shelter in the event of disaster. Among the seismic retrofit methods, the internal steel braced frame type method is used for its relatively easy construction and excellent performance. In this study, the maximum shear force and displacement were compared and examined by applying the brace frame to existing concrete school buildings. As a result, we verified the adequacy of the analytical model and compared and examined the effect of brace-height ratio on the span of the existing school buildings. The adequacy of the maximum shear force and displacement relationship can be confirmed in the model with a length of 0.3. In addition, seismic frame was applied to the actual non-seismic reinforced concrete school building, and the seismic performance was evaluated by nonlinear static analysis(Push-over analysis) according to the ratio of brace-height. As a result, the increase of the brace-height according to the brace-height ratio has the effect of increasing the maximum shear force and maximum load at the performance point. But the collapse of the braced frame due to the increase in the lateral stiffness occurred, indicating that seismic retrofit according to the proper brace-height is necessary. Therefore, in the seismic retrofit design of brace frame of existing school building, it is necessary to select the proper brace-height after retrofit analysis according to the brace-height ratio.

• Magazine of the Korea Concrete Institute
• /
• v.5 no.4
• /
• pp.167-178
• /
• 1993

The objective of this paper is to look into the possibility of the detailed and practical optimum design of rt:inforced concrete beam using methods oi discrete mathematical programming. In this discrete optimum formulation, the design variables are the overall depth, width and effective depth of members, and area of longitudinal reinforcement. In addition, the details such as the amount of web reinforcement and cutoff points of longitudinal reinforcement are also considered as variables. Total cost has been used as the objective function. The constraints include the code requirments such as flexural strength, shear strength, ductility, serviceability, concrete cover. spacing, web reinforcement, and development length and cutoff points of longitudinal renforcement. An optimization algorithm is presented for effective optimum design of R.C. beam with discrete de sign variables. First, the continuous variable optimization can be achieved by Feasible Direction Method. Using the results obtained from the continuous variable optimization, a branch and bound method is used to obtained the discrete design values. The proposed algorithm is applied to test problem for reliability, and the results are compared with those of graphical method and rounded-up method. And a simply supported R.C. beam and a two-span continuous R.C. beam are presented as numerical examples for effectiveness and applicability. It is considered that the presented algorithm can be effectively applied to the discrete optimum design of R.C. beams.

• Journal of Korean Association for Spatial Structures
• /
• v.8 no.5
• /
• pp.47-58
• /
• 2008

Spatial structure is an appropriate shape that resists external force only with in-plane force by reducing the influence of bending moment, and it maximizes the effectiveness of structural system. With this character of the spatial structure, generally long span is used. As a result, large deflection is accompanied from the general frame. the structure is apt to result in a large deflection even though this structure experiences a small displacement in absence. Usually, nonlinear analysis in numerical analysis means geometric nonlinearity and material nonlinearity and complex nonlinearity analysis considers both of them. In this study, nonlinear equation of equilibrium considering geometric nonlinearity as per finite element method was applied and also considered the material nonlinearity using the relation of stress-strain in element. It is applied to find unstable result for tracing load-deflection curve in the numerical analysis tech. especially Arc-length method, and result of the analysis was studied by ABAQUS a general purpose of the finite element program. It is found that the present analysis predicts accurate nonlinear behavior of plane and space truss.

• Journal of Bio-Environment Control
• /
• v.27 no.3
• /
• pp.206-212
• /
• 2018

As many consumers prefer good quality food, farms have used various facilities to cultivate products for satisfying their desires. Among them, the most representative facilities are plastic and glass multi-span greenhouse. The height of both plastic greenhouse and glass greenhouse is around three meters high in Korea. As a result, the crop productivity is limited. The solution is to increase the height of the greenhouses to improve the greenhouses' environment. The device for raising columns consists of a stop device, a pneumatic cylinder, and a vertical member. Pneumatic cylinders were designed with a diameter of 160 mm and a stroke length of 50 mm, taking into consideration the safety factor of 1.5. In addition, the air flow was controlled by nozzle to achieve a time of less than 30 seconds per stroke. It was calculated that $21.5L{\cdot}min^{-1}$ of air was needed to complete in less than 30 seconds. Accordingly, the diameter of the nozzle is designed to be 0.5 mm. When the pressure was 0.9 MPa, the average raising force was 13,805N, which was close to the calculated value of 15,612N. The field test results show that any inconsistency in the row columns was not generated. and that it is considered applicable to the actual glass and plastic greenhouses.

• Journal of the Korean Society for Railway
• /
• v.14 no.6
• /
• pp.545-554
• /
• 2011

In order to get dynamic serviceability of a train travelling on a railway bridge, comfort limits with the deflection of bridge and vertical acceleration on car body are proposed in Eurocode, Shinkansen design criteria, The design guideline of the Honam High-speed railway. The design guideline of the Honam High-speed railway has quoted Eurocode. Therefore it is expected that supplementation of comfort limit of railway bridge according to expansion of span length and the improvement traveling speed of trains in the future would relatively fall behind developed countries in railway. Therefore, in order to secure technological competitiveness in world market, the study was conducted to propose the deflection limit based on vibration serviceability of railway bridges that can consider bridge-train interaction and travelling speed increase. The parameter study and bridge-train dynamic interaction analysis was conducted to figure out the correlation of vertical acceleration on car body and bridge displacement according to the increase in travelling speed. Also, the trend of increasing vertical acceleration on car body according to the increase in travelling speed was confirmed, and the amplification coefficient of vertical acceleration on car body was suggested. And the deflection form and vibration of the bridge were assumed to be in harmonic motion, and transfer function and the amplification coefficient were used to develop the dynamic serviceability deflection limit of the high-speed railway bridge as a formula.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.3 no.2
• /
• pp.109-114
• /
• 2015

Recently, numerous studies were dedicated on the HVFA concrete using high volume CCPs. In initial studies, main topics are dependent on material properties of HVFA concrete, but several studies were dedicated on the structural behavior of HVFA concrete such as elasticity modulus, stress-strain relationship and structural behavior nowadays. Therefore, in this paper, on the basis of recent studies on the structural behavior, 2 large-scale test members were manufactured with 7.5m span length and fly ash replacement ratio 50%, concrete compressive strength 50MPa in order to apply to the practical structure and evaluate possibility of application. From the test results, although there were small differences between test results and existing research results on the stress-strain relationship, the application to practical structure is not hard. In flexural test, as the produced pattern of displacement and strain were similar to those of general concrete without fly ash, the difference between 50% fly ash concrete and general concrete is very small. And the concrete shear strength obtained by test was similar to that of design code, so existing design code will be also able to apply.