• Earthquakes and Structures
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• v.17 no.6
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• pp.611-621
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• 2019

Precast concrete structure has many advantages, but the assembled seam will affect potentially the overall seismic performance of structure. Based on the sidewall joint located in the bottom of assembled monolithic subway station, the main objectives of this study are, on one hand to present an experimental campaign on the seismic behavior of precast sidewall joint (PWJ) and cast-in-place sidewall joint (CWJ) subjected to low-cycle repeated loading, and on the other hand to explore the effect of shape and position of assembled seam on load carrying capacity and crack width of precast sidewall joint. Two full-scale specimens were designed and tested. The important index of failure pattern, loading carrying capacity, deformation performance and crack width were evaluated and compared. Based on the test results, a series of different height and variably-shape of assembled seam of precast sidewall joint were considered. The test and numerical investigations indicate that, (1) the carrying capacity and deformation capacity of precast sidewall and cast-in-place sidewall were very similar, but the crack failure pattern, bending deformation and shearing deformation in the plastic hinge zone were different obviously; (2) the influence of the assembled seam should be considered when precast underground structures located in the aquifer water-bearing stratum; (3) the optimal assembled seam shape and position can be suggested for the design of precast underground concrete structures according to the analysis results.

• Steel and Composite Structures
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• v.46 no.4
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• pp.539-551
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• 2023

In order to study the fire resistance of castellated composite beams with ortho-hexagonal holes and different beam-end restraints, temperature rise tests with constant load were conducted on full-scale castellated composite beams with ortho-hexagonal holes and hinge or rigid joint constraints to investigate the temperature distribution, displacement changes and failure patterns of castellated composite beams with two different beam-end constraints during the whole course of fire. The results show that (1) During the fire, the axial pressure and horizontal expansion deformation generated in the rigid joint constrained composite beam were larger than those in the hinge joint constrained castellated composite beam, and their maximum horizontal expansion displacements were 30.2 mm and 17.8 mm, respectively. (2) After the fire, the cracks on the slab surface of the castellated composite beam with rigid joint constraint were more complicated than hinge restraint, and the failure more serious; the lower flange and web at the ends of the castellated steal beams with hinge and rigid joint constraint produced serious local buckling, and the angles of the ortho-hexagonal holes at the support cracked; the welds at both ends of the castellated composite beam with rigid joint constraint cracked. (3) Based on the simplified calculation method of solid-web composite beam, considering the effect of holes on the web, this paper calculated the axial force and displacement of the beam-end constrained castellated composite beams under fire. The calculation results agreed well with the test results.

• Journal of the Korea Concrete Institute
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• v.27 no.5
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• pp.471-480
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• 2015

The building structure is planned to maximize the use of space in recent. It was developed of a hybrid OCB (Optimized Composite Beam) for trying to take advantage of the maximize space. The OCB is composed of the steel h-beam section reinforced by open strands in negative moment zone and the psc concrete section in positive zone. Flexural behaviors of typical architectural bybrid OCB section was investigated. The 15 m OCB specimen was tested under three point static loading system. Following results are obtained from the tests; 1) The OCB with 15 m span develop initial flexural crackings under the 171% of full service loading. 2) Overall deflections of OCB under the service loads are less than those of the allowable limit in KCI Code provision. 3) The crack patterns, failure mode and ultimate load capacity of test specimen and F.E. model in this paper and they are compared to each other. The OCB is verified of structural reliability from the experimental results.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.147-160
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• 2008

This paper presents the results of full-scale loading tests performed on 54 passive anchors and 4 group anchored footings grouted to various lengths at several sites in Korea. The test results, the failure mechanisms as well as uplift capacities of rock anchors depend mostly on rock type and quality, embedded fixed length, properties of the discontinuities, and the strength of rebar. Anchors in poor quality rocks generally fail along the grout/rock interfaces when their depths are very shallow (a fixed length of less than 1 m). However, even in such poor rocks, we can induce a more favorable mode of rock pull-up failure by increasing the fixed length of the anchors. On the other hand, anchors in good quality rocks show rock pull-up failures with high uplift resistance even when they are embedded at a shallow depth. Laboratory test results revealed that a form of progressive failure usually occurs starting near the upper surface of the grout, and then progresses downward. The ultimate tendon-grout bond strength was measured from $18{\sim}25%$ of unconfined compressive strength of grout. One of the important findings from these tests is that the measured strains along the corrosion protection sheath were so small that practically the reduction of bond strength by the presence of sheath would be negligible. Based on test results, the main parameters governing the uplift capacity of the rock anchor system were determined. By evaluation of the ultimate uplift capacity of anchor foundations in a wide range of in situ rock masses, rock classification suitable for a transmission tower foundation was developed. Finally, a very simple and economical design procedure is proposed for rock anchor foundations subjected to uplift tensile loads.

• Journal of the Korean GEO-environmental Society
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• v.15 no.9
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• pp.69-75
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• 2014

Rock fall protection system installed against rock slope is one of the most conventional way to protect nearby infra structures. Despite of wide application of typical rectangular nets, virtually installed to protect rock slope face, several problems have also been pointed out up to date. Rectangular draped nets are vulnerable to a sudden external shock such as rock fall, because it doesn't have any systematical buffers or shock absorbers. Furthermore, it has been widely recognized from the some cases of rock fall accident in Korea that rock fall protection nets cause wide range of failure in the rock slope faces due to insufficient pullout bearing capacity of fixing parts. Therefore, in this study, we tried to make a consideration about the problems of existing standard rock fall protection nets in Korea, and develop a new type of hexagonal net with a shock absorber based on design rock fall energy. In this paper, laboratory and full scale test procedure is described to analysis the performance of newly developed hexagonal rock fall net, and the key results are presented and discussed.

• Steel and Composite Structures
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• v.36 no.3
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• pp.261-272
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• 2020

A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

• Journal of the Korean GEO-environmental Society
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• v.24 no.9
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• pp.15-24
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• 2023

The behavior of buried pipes is directly influenced by the nonlinearity and complex characteristics of the surrounding soil. However, the simplified beam-spring model, which ignores the nonlinearity and complex behavior of soil, is commonly used in practice. In response, several studies have employed continuum analysis methods to account for the nonlinear and complex behavior of the soil. This paper presents various numerical continuum analysis techniques and verifies their comparison with full-scale tests. The study found that reaction force results close to the full-scale test could be obtained by applying contact surface characteristics that take into account the interaction between the ground and the buried pipe. In the case of sharing pipe and soil node method and ignoring the interaction between pipe and soil, excessive reaction force was derived, and the failure shapes were different. In addition, this study applied the dynamic explicit analysis method, ALE method, and CEL method. It was confirmed that the displacement-reaction relationship and failure shape are similar to those of the static analysis.

• Geomechanics and Engineering
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• v.11 no.2
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• pp.211-234
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• 2016

A total of 99 full-scale field load tests at 22 sites were compiled for this study to elucidate several issues related to the load-displacement behaviour of belled piers under axial uplift loading, including (1) interpretation criteria to define various elastic, inelastic, and "failure" states for each load test from the load-displacement curve; (2) generalized correlations among these states and determinations to the predicted ultimate uplift resistances; (3) uncertainty in the resistance model factor statistics required for reliability-based ultimate limit state (ULS) design; (4) uncertainty associated with the normalized load-displacement curves and the resulting model factor statistics required for reliability-based serviceability limit state (SLS) design; and (5) variations of the combined ULS and SLS model factor statistics for reliability-based limit state designs. The approaches discussed in this study are practical and grounded realistically on the load tests of belled piers with minimal assumptions. The results on the characterization and uncertainty of uplift load-displacement behaviour of belled piers could be served as to extend the early contributions for reliability-based ULS and SLS designs.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.103-109
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• 2008

A study has been conducted on the bulging process of regenerative cooling nozzle which is essential for the manufacturing of liquid rocket thrust chamber. Tension tests have been performed for the material to be used for the development of the bulging process and mechanical properties are obtained by the test. Two or three bulging tools were required to complete the bulging process. The necking of the material was a major failure encountered in the bulging process and a research has revealed that grain size of the material has considerable effect on its occurrence. The presently developed bulging process with a controlled grain size material has been successfully applied to the manufacturing of subscale and 30-tonf full scale regeneratively cooled nozzle while demonstrating the applicability and usefulness of the presently developed bulging process.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.746-749
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• 2004

A new-type of FRP-concrete composite bridge deck system is proposed and its behaviors are experimentally studied. The new-typedeck consists of FRP as a permanent form and main tension resisting member and concrete as a compression resisting member. A suitable bonding method such as silica coating is applied to the interface between FRP and concrete to ensure composite behavior. The proposed deck system uses the box-shape FRP member, while a typical FRP-concrete composite deck uses the I-shape FRP member. Theproposed deck system has inherent advantages of a FRP-concrete composite deck like corrosion free and easy construction. The new-type deck shows the equal performances compared to a previous one, and has the advantage of reducing self-weight. In this study, the static tests on 3-span FRP-concrete decks in full scale are carried out, so that load-displacement relation, stress distribution, failure mode and design criteria are analyzed. The test results show that the deflection design criterion (L/800, L: span length) is satisfied at the service load state. No concrete tensile crack occurs in the negative moment region above the main girder, regardless of no tensile reinforcement at upper concrete portion.