• Journal of the Korea Concrete Institute
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• v.26 no.6
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• pp.761-769
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• 2014

Ultra high performance concrete (UHPC) has been developed to overcome the low strengths and brittleness of conventional concrete. Considering that UHPC, owing to its composition and the use of steel fibers, develops a compressive strength of 180 MPa as well as high stiffness, the top flange of the steel girder may be superfluous in the composite beam combining a slab made of UHPC and the steel girder. In such composite beam, the steel girder takes the form of an inverted-T shaped structure without top flange in which the studs needed for the composition of the steel girder with the UHPC slab are disposed in the web of the steel girder. This study investigates experimentally and analytically the flexural behavior of this new type of composite beam to propose details like stud spacing and slab thickness for further design recommendations. To that goal, eight composite beams with varying stud spacing and slab thickness were fabricated and tested. The test results indicated that stud spacing running from 100 mm to 2 to 3 times the slab thickness can be recommended. In view of the relative characteristic slip limit of Eurocode-4, the results showed that the composite beam developed ductile behavior. Moreover, except for the members with thin slab and large stud spacing, most of the specimens exhibited results different to those predicted by AASHTO LRFD and Eurocode-4 because of the high performance developed by UHPC.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.2
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• pp.23-30
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• 2008

UHPC has high performance, high strength and excellent mechanical properties. Moreover UHPC(Ultra High Performance Cementitious Composite) has advantage to reduce cross section under the same load compared with other kinds of concrete. But silica fume which is imported from foreign country has a abundant portion in UHPC mixture in comparison with normal concrete. This is one of the main reason to raise the construction cost. Superior mechanical properties of UHPC due to the optimum filling composition can be changed by replacing the very fine ingredient. The purpose of this research is to grasp the characteristic of UHPC which silica fume and silica flour is replaced with limestone powder. This experiment can be divided into three classes according to the kinds of replacement. The compressive strength and flow of all types were measured and microstructure and hydration phenomena for comparing RPC were analyzed by SEM, XRD, NMR method. As a result, the replacement can be considered to be effective by for the decrease of the UHPC structure construction cost and improvement of the fresh UHPC.