• Advances in concrete construction
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• v.15 no.6
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• pp.391-404
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• 2023

In this study, the modeling of the transverse connection of fully precast steel-UHPC (Ultra-High-Performance Concrete) lightweight composite bridges were conducted. The transverse connection between precast components plays a critical role in the overall performance and safety of the bridge. To achieve an accurate and reliable simulation of the interface behavior, the cohesive model in ABAQUS was employed, considering both bending-tension and compression-shear behaviors. The parameters of the cohesive model are obtained through interface bending and oblique shear tests on UHPC samples with different surface roughness. By validating the numerical simulation against actual joint tests, the effectiveness and accuracy of the proposed model in capturing the interface behavior of the fully precast steel-UHPC lightweight composite bridge were demonstrated.

• Computers and Concrete
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• v.25 no.5
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• pp.479-484
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• 2020

This work performed to analyses the impact of hooked end steel fibres on the mechanical properties of high performance concrete. The mechanical properties considered incorporate compressive strength, split tensile strength and flexural strength. Taking in to thought parameters, such as, volume fraction of fibres, fibre aspect ratio and grade of concrete, a logical strategy called Taguchi technique was utilized to discover the ideal blend of factors. L9 Orthogonal Array (OA) of Taguchi network comprising of three variables and three dimensions is utilized in this work. The evaluations of concrete considered were M60, M80 and M100. M60 contained 15% of metakaolin as bond swap though for M80 it was 5% of metakaolin and for M100 it was 10% metakaolin and 10% of silica smolder. The volume portion of fiber was fluctuated by 0.5%; 1% and 1.5% and the viewpoints proportions considered were 50, 60 and 80. The test outcomes demonstrate that incorporation of steel fibres enhance significantly the the strength characteristics of concrete, predominantly the splitting tensile strength and flexural strength. In light of relapse investigation of the test information scientific models were produced for compressive strength, split tensile strength and flexural strength of the steel fibre-reinforced high performance concrete.

• Steel and Composite Structures
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• v.37 no.3
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• pp.323-339
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• 2020

In steel framed-tube structures (SFTSs), the plastic hinges at beam-ends cannot be adequately improved because of the large cross sections of spandrel beams, which results in the lower ductility and energy dissipation capacities of traditional SFTSs. To address this drawback, high-strength steel fabricated SFTSs with bolted web-connected replaceable shear links (HSFTS-SLs) have been proposed. In this system, shear links use conventional steel and are placed in the middle of the deep spandrel beams to act as energy dissipative components. In this study, 2/3-scaled HSFTS-SL specimens were fabricated, and cyclic loading tests were carried out to study the seismic performance of both specimens. The finite element models (FEMs) of the two specimens were established and the numerical results were compared with the test results. The results showed that the specimens had good ductility and energy dissipation capacities due to the reliable deformation capacities. The specimens presented the expected failure modes. Using a shorter shear link can provide a higher load-carrying capacity and initial elastic lateral stiffness but induces lower ductility and energy dissipation capacity in HSFTS-SLs. The performance of the specimens was comparable to that of the original sub-structure specimens after replacing shear links. Additionally, the expected post-earthquake recoverability and resilience of the structures could be achieved by replacing shear links. The acceptable residual interstory drift that allows for easy replacement of the bolted web-connected shear link was 0.23%. The bolted web-connected shear links had reliable hysteretic responses and deformation capacities. The connection rotation had a notable contribution to total link rotation. The results of the numerical analysis run for the proposed FEMs were consistent with the test results. It showed that the proposed FEMs could be used to investigate the seismic performance of the HSFTS-SL.

• Steel and Composite Structures
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• v.21 no.2
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• pp.289-302
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• 2016

A new kind of partially precast or prefabricated castellated steel reinforced concrete beam, which is abbreviated here as CPSRC beam, was presented and introduced in this paper. This kind of CPSRC beam is composed of a precast outer-part and a cast-in-place inner-part. The precast outer-part is composed of an encased castellated steel shape, reinforcement bars and high performance concrete. The cast-in-place inner-part is made of common strength concrete, and is casted with the floor slabs simultaneously. In order to investigate the shear performance of the CPSRC beam, experiments of six CPSRC T-beam specimens, together with experiments of one cast-in-place SRC control T-beam specimen were conducted. All the specimens were subjected to sagging bending moment (or positive moment). In the tests, the influence of casting different strength of concrete in the cross section on the shear performance of the PPSRC beam was firstly emphasized, and the effect of the shear span-to-depth ratio on that were also especially taken into account too. During the tests, the shear force-deflection curves were recorded, while the strains of concrete, the steel shapes as well as the reinforcement stirrups at the shear zone of the specimens were also measured, and the crack propagation pattern together with the failure pattern was as well observed in detail. Based on the test results, the shear failure mechanism was clearly revealed, and the effect of the concrete strength and shear span-to-depth ratios were investigated. The shear capacity of such kind of CPSRC was furthermore discussed, and the influences of the holes on the steel shape on the shear performance were particularly analyzed.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.1962-1971
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• 2022

The liquid lead-lithium (Pb-17Li) blanket has many applications in fusion reactors due to its good tritium breeding performance, high heat transfer efficiency and safety. The compatibility of liquid Pb-17Li alloy with the structural material of blanket under magnetic field is one of the concerns. In this study, corrosion experiments China low activation martensitic (CLAM) steel and 316L steel were carried out in a forced convection Pb-17Li loop under 1.0 T magnetic field at 480 ℃ for 1000 h. The corrosion results on 316L steel showed the characteristic with a superficial porous layer resulted from selective leaching of high-soluble alloy elements and subsequent phase transformation from austenitic matrix to ferritic phase. Then the porous layers were eroded by high-velocity jet fluid. The main corrosion mechanism of CLAM steel was selective dissolution-base corrosion attack on the microstructure boundary regions and exclusively on high residual stress areas. CLAM steel performed a better corrosion resistance than that of 316L steel. The high Ni dissolution rate and the erosion of corroded layers are the main causes for the severe corrosion of 316L steel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.5
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• pp.110-118
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• 2010

This research dealt with the effect of steel-fiber reinforcement on the compressive strength of ultra high performance cementitious composites (UHPCC) and compared with that in normal steel-fiber reinforced concrete(SFRC). With wide range of compressive strength of UHPCC, experiments on the fiber reinforcement effect confirmed that the compressive strength in UHPCC is also improved by adding fibers as in normal SFRC. The experimental results were compared with previous researches about reinforcement effect by adding fibers, which are limited within 100MPa compressive strength. The comparison revealed the linear relationship between $f'_{cf}-f'_c$ and RI regardless of the magnitude of compressive strength, from which a general equation to express the effect of fiber reinforcement, applicable to various SFRC's with wide range of compressive strength including UHPCC.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.23-28
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• 2001

Since the steel fiber used in concrete to improve shear and ductility capacity, a number of laboratory tests have been studied to define shear strengthening effect according steel fiber contents in concrete. This study investigates shear strengthening effect of steel fiber in RC columns according to compression strength of concrete. From the structural performance test, following conclusions can be made; the maximum enhancement of shear strengthening effect can be achieved at about 1.0 %~l.5 % of steel fiber contents in comparison with shear capacity ratio, and ductility capacity slightly improved as steel fiber contents increased.

• Journal of the Earthquake Engineering Society of Korea
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• v.8 no.6 s.40
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• pp.45-54
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• 2004

Recently, as steel structures become higher and more long-spanned, application of high-strength steels is increasing gradually. For seismic design of steel structures using high-strength steels(POSTEN60, POSTEN80), analytical method, can describe the large deformation and inelastic cyclic behavior generated by non-proportional cyclic loading, are required. In this paper, cyclic plasticity model was proposed by results of monotonic loading tests ant cyclic loading tests. Three-dimensional finite element analysis is developed by using proposed model and finite deformation theory and verified as compare with experiment result. Using 3-dimensional elastic-plastic finite deformation analysis, seismic analysis of high-strength steel pipe-section piers are carried out. Also, seismic performance of high-strength steel pipe-section piers in parameter of diameter-thickness ratio was clarified.

• Journal of Korean Society of Steel Construction
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• v.25 no.1
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• pp.71-80
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• 2013

Fire-resistant (FR) test data for a square concrete-filled steel tube (CFT) columns consisting of high-strength steel (fy>650MPa) and high strength concrete (fck>100MPa) under axial loads are insufficient. The FR behavior of square high-strength CFT members was investigated experimentally for two specimens having ${\Box}-400{\times}400{\times}15{\times}3,000mm$ with two axial load cases (5,000kN and 2,500kN). The results show that the FR performance of the high-strength CFT was rapidly decreased at earlier time (much earlier at high axial load) than expected due to high strength concrete spalling and cracks. In addition, a fiber element analysis (FEA) model was proposed and used to simulate the fiber behaviour of the columns. For steel and concrete, the mechanical and thermal properties recommended in EN 1994-1-2 are adopted. Test results were compared to those of numerical analyses considering a combination of temperature and axial compression. The numerical model can reasonably predict the time-axial deformation relationship.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.710-713
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• 2000

The corrosion protection methods of reinforcing steel in concrete are the various methods such as increasing thickness of cover concrete, using of reinforcing bars coated with epoxy, dosage of corrosion inhibitor as concrete admixture, cathodic protection method and etc. The most economical method of them will be the corrosion protection method using corrosion inhibitor as concrete admixture. Therefore, the purpose of this research is to investigate the performance of corrosion protection of ordinary strength and high strength concrete using corrosion inhibitor, respectively. For this purpose, after manufacturing ordinary strength and high strength concrete with and without corrosion inhibitor, the accelerated corrosion tests for reinforcing steel were conducted according to the periodic cycles (140 day) of wetting ($65^{\circ}C$, 90% R.H.) and drying period ($15^{\circ}C$, 65% R.H.). As a result, th high strength concrete using corrosion inhibitor showed an excellent performance of corrosion protection.