• Steel and Composite Structures
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• v.53 no.4
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• pp.421-434
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• 2024

In order to study the seismic performance of the damaged steel concrete special-shaped beam-column joints reinforced by manually compacted ultra-high performance concrete (UHPC), cyclic hysteresis loading tests were carried on two profiled concrete beam-column joint specimens before and after the reinforcement. The failure mode, load carrying capacity, deformation, hysteresis curves, skeleton curves, strength degradation, stiffness degradation, and energy dissipation capacity of the specimens were compared before and after reinforcement. The results show that the bonding performance between UHPC material and ordinary concrete was very good. After UHPC reinforcement, the bearing capacity of the damaged joints can be basically restored to the intact state, and the energy-consuming capacity increased, but the stiffness degradation was obvious. It is recommended that when using UHPC for joint reinforcement, the effect of forming ring wrap in the joint area is better. The research conclusion can provide reference for the design and popularization of UHPC and has certain theoretical and practical value.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.171-178
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• 2008

Compressive strength of concrete has been regarded as a very important parameter of the quality control both in new and existing concrete pavement. It has been used a lot as the concrete strength evaluation both in the various-mixture-using laboratory and construction field using the same mixture. An error usually occurs in the test experiments of the strength, even in the test experiments with evenly mixed and compacted specimens of the compressive strength. It is caused by the 'manually operated' compressing testing, or by the specimens preparation with eccentricity. When compressive strength of evenly mixed concrete is investigated by the curing ages at the construction field, there have to be lots of specimens. And it needs much labor and cost. To substitute the endlessly repeated test experiments of compressive strength, presumption of compressive strength, by nondestructive tests, is needed. In this study, elastic waves were used among various nondestructive tests. Compressive strength of concrete was presumed according to the curing ages, by using the shear wave velocity which is not affected by restricted conditions. In the result, shear wave velocity is very closely related to the compressive strength at the evenly mixed concrete.