• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.321-329
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• 2003

To effectively use the cross section of concrete decks, analytical and experimental studies on prestressed steel-box-girder bridges were performed in this study. The method of applying prestress was determined in the analytical study and the longitudinal behavior of the prestressed steel-box-girder bridge was considered in the experimental study. The object model for these studies was a two-span continuous bridge. The method of applying prestress determined herein was divided into two parts: one is that apply prestress to the concrete deck at its intermediate support, and the other is that apply prestress to the lower flange of the steel-box-girder bridge at its end support. The prototype bridge for the experiment was simulated based on the rule of similitude and was fabricated according to construction steps to apply prestress effectively. From the results of the experimental study, it has demonstrated that the prestressed steel-box-girder bridge provides better performance than the general steel-box-girder bridge in view of the increase of the design live load, the reduction of the tensile stress of the concrete deck at intermediate support, and the reduction of the displacement.

• Steel and Composite Structures
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• v.13 no.3
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• pp.239-258
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• 2012

In this paper, experimental investigations on high strength steel (HSS) stud connected steel-concrete composite (SCC) girders to understand the effect of shear connector density on their flexural behaviour is presented. SCC girder specimens were designed for three different shear capacities (100%, 85%, and 70%), by varying the number of stud connectors in the shear span. Three SCC girder specimens were tested under monotonic/quasi-static loading, while three similar girder specimens were subjected to non-reversal cyclic loading under simply supported end conditions. Details of casting the specimens, experimental set-up, and method of testing, instrumentation for the measurement of deflection, interface-slip and strain are discussed. It is found that SCC girder specimen designed for full shear capacity exhibits interface slip for loads beyond 25% of the ultimate load capacity. Specimens with lesser degree of shear connection show lower values of load at initiation of slip. Very good ductility is exhibited by all the HSS stud connected SCC girder specimens. It is observed that the ultimate moment of resistance as well as ductility gets reduced for HSS stud connected SCC girder with reduction in stud shear connector density. Efficiency factor indicating the effectiveness of high strength stud connectors in resisting interface forces is estimated to be 0.8 from the analysis. Failure mode is primarily flexure with fracturing of stud connectors and characterised by flexural cracking and crushing of concrete at top in the pure bending region. Local buckling in the top flange of steel beam was also observed at the loads near to failure, which is influenced by spacing of studs and top flange thickness of rolled steel section. One of the recommendations is that the ultimate load capacity can be limited to 1.5 times the plastic moment capacity of the section such that the post peak load reduction is kept within limits. Load-deflection behaviour for monotonic tests compared well with the envelope of load-deflection curves for cyclic tests. It is concluded from the experimental investigations that use of HSS studs will reduce their numbers for given loading, which is advantageous in case of long spans. Buckling of top flange of rolled section is observed at failure stage. Provision of lips in the top flange is suggested to avoid this buckling. This is possible in case of longer spans, where normally built-up sections are used.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.237-248
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• 1997

Three types of fatigue cracks frequently observed in the crane runway girders are verified experimentally using two testing-purpose girders with the size of $6400{\times}600{\times}300$ in millimeters. The fatigue cracks are observed in the vicinity of load-bearing points, at the end of gusset plates and at the fillet welded joints between the lower flange and the web. The load-bearing-point cracks are initiated at the intersection of the fillet welds between the upper flange and the web, where the vertical stiffener is located. The cracks grow up toward the diagonal direction of the web. The cracks observed at the fillet welded joints grow up perpendicularly to the crane runway girder. Compared with the JSSC fatigue design code, the joint class is classified as follows: E for the vicinity of load-bearing points, G or H for the end of gusset plates and D for the lower fillet welded joints. The tests reveal that the class of joint classification at the end of gusset plates and at the lower flange coincides with the fatigue design code.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.39-51
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• 1983

Increasing of load on the highway bridge necessitate the strengthening of load capacity of bridge by some method. The method of strengthening is the usage of pre-stressing high tensile steel line. Having finished pre-stressing work, line is anchored both end, then it composed a member of bridge structure when loading. This paper includes the method and mechanism of strengthening of I-beam span(same originality of plate girder), could be summerized as following; (a) Simple girder, 2 span and 3 span continuous girder increasing the load capacity by more than 80 % for concentrated load. (b) For uniformly distributed load, when all span loaded, load capacity is increase more than 80% to 100% except 3 span continuous.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.109-118
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• 2009

A new bridge system described in this paper uses concrete-filled steel tube (CFT) girders as a replacement for conventional girders. Experimental investigations were carried out to comprehend the flexural behavior of CFT girder. Specimens were manufactured considering several parameters such as the strength of filling material, the eventual presence and number of inner shear connectors to evaluate the bending bearing capacity of CFT girder. The experimental investigation consisted of designing and constructing a test specimen and loading it to collapse in bending to check the applicability of the system. Test results showed that concrete filled steel tube girders have good ductility and maintain their strength up to the end of the loading. The stiffening effect of the ㄱ-shaped perfobond rib is determined to contribute relatively to the increase of the bending bearing capacity.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.343-351
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• 2010

Bending and axial compressive stresses are distributed across the whole upper flange of a box girder bridge which has the span-to-depth ratio (B/L) of below 0.5, according to Korea Bridge Design Specifications (Minister of Land, Transport and Maritime Affairs, 2005). Shear lag phenomenon, however, can take place in the construction phase of cable-stayed bridge, in which stresses combining bending moment due to dead weight and cable vertical compression are induced. This study aims to analyze the effective width of flange over which composite stresses are given, which should be calculated during the construction phase of stiffening girder of single plane cable-stayed box girder bridge. The study results indicate that the full width of stiffening girder can be regarded as the effective flange width when the span-to-depth ratio for the deck is below 0.38. In other words, the area, where shear lag is taken into consideration, is larger than the width of box girder in single plane cable-stayed box girder bridges. Therefore, the current practice of considering the full width as the effective flange width regardless of changes of the span-to-depth ratio during the construction stage can produce an unsafe bridge. If the effective flange width is determined according to the single span structural system in the early stage of construction when the span-to depth ratio for the deck is high and composite stresses of every part expect each end of the bridge are calculated, it can result in a safe structural design. Since the span-to-depth ratio gradually decreases, however, it is appropriate to determine the effective width of flange on the basis of the full width and the cantilever structural system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.707-717
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• 2006

As an alternative to conventional prestressed concrete (PSC) girders, various types of PSC girders are either under development or have already been applied in bridge structures. Incrementally prestressed concrete girder is one of these newly developed girders. According to the design concept, these new types of PSC girders have the advantages of requiring less self-weight while having the capability of longer spans. However, the dynamic interaction between bridge superstructures and passing trains is one of the critical issues concerning these railway bridges designed with more flexibility. Therefore, it is very important to evaluate modal parameters of newly designed bridges before doing dynamic analyses. In the present paper, a 25 meters long full scale PSC girder was fabricated as a test specimen and modal testing was carried out to evaluate modal parameters including natural frequencies and modal damping ratios at every prestressing stage. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer is applied, in order to obtain precise frequency response functions and the modal parameters are evaluated varying with construction stages. Prestressed force effects on changes of modal parameters are analyzed at every incremental prestressing stage. With the application of reliable properties from modal experiments, estimation of dynamic performances of PSC girder railway bridges can be obtained from various parametric studies on dynamic behavior under the passage of moving train. Dynamic displacements, impact factor, acceleration of the slab, end rotation of the girder, and other important dynamic performance parameters are checked with various speeds of the train.

• Steel and Composite Structures
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• v.22 no.1
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• pp.45-61
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• 2016

The domestic and foreign scholars conducted many studies on mechanical properties of wave web steel beam and high-strength spiral stirrups confined concrete columns. Based on the previous research work, studies were conducted on the anti-seismic property of the end plate bolt connected wave web steel beam and high-strength spiral stirrups confined concrete column nodes applied with pre-tightening force. Four full-size node test models in two groups were designed for low-cycle repeated loading quasi-static test. Through observation of the stress, distortion, failure process and failure mode of node models, analysis was made on its load-carrying capacity, deformation performance and energy dissipation capacity, and the reliability of the new node was verified. The results showed that: under action of the beam-end stiffener, the plastic hinges on the end of wave web steel beam are displaced outward and played its role of energy dissipation capacity. The study results provided reliable theoretical basis for the engineering application of the new types of nodes.

• Journal of architectural history
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• v.26 no.2
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• pp.7-14
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• 2017

Rafter is a member for roof and plays a role in protecting shaft members under rafter such as pillar, beam and girder from natural environment and to fix by supporting finished materials of roof. It is common in the Korean architecture that rafter cross-section is paired with circular form and Buyeon cross-section is paired with the square shape. However, while there are not many, some architectures have rafter end header in the square shape. The aim of this study is to examine the square shape cases of rafter end header with special reference to stone structure. As a result, among stone structure related to Bangyeon, the majority case is seen at Palgakwondang type Seungtap. It was shown in the Seungtap of monk of Gusanseonmun school in the later Unified Silla to the early Goryeo period that succeeded Seodang Jijang.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.105-118
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• 2014

The number of the deteriorated bridge has been sharply increased due to the increase in the bridge service period in Korea. Local corrosion problem of structural member can be occurred according to atmospheric corrosion environments based on the installation location of steel bridges. Especially, in case of the plate girder bridge, corrosion damage is concentrated on the web panel and stiffener at girder end. An asymmetrical shear resistant web section in the plate girder bridge can be caused from the local corrosion of the web panel, because local corrosion is not symmetrically occurred to the bridge. In this study, therefore, the shear buckling strength and behavior of a plate girder with asymmetrically corroded web panel was numerically evaluated using FE analysis, which was considering an aspect ratio and corrosion damage level of web panel. The shear buckling strength reduction of an asymmetrical shear resistant web panel was compared and evaluated according to corroded volume ratio for a web panel and for diagonal tension field of a web panel.