Performance of BFRP Retrofitted RCC Piles Subjected to Axial Loads

This paper deals with the behaviour of basalt fibre reinforced polymer (BFRP) composites retrofitted RCC piles subjected to axial compression loads. Currently the awareness of using FRP increases rapidly in engineering fields and also among public. Retrofitting becomes vital for aged and damaged concrete structures, piles, and so forth, to improve its load carrying capacity and to extend the service life. The load carrying capacity of piles retrofitted with basalt unidirectional fabric was studied experimentally. 15 nos. of RCC end bearing pile elements were cast with same reinforcement for axial compression experiment. Three piles were used as conventional elements, another 3 piles were used as double BFRP wrapped pile elements, and remaining 9 piles were used as retrofitted piles with BFRP double wrapping after preloaded to 30%, 60%, and 90% of ultimate load of conventional element. The effects of retrofitting of RCC pile elements were observed and a mathematical prediction was developed for calculation of retrofitting strength. The stress vs. strain relationship curve, load vs. deformation curve, preloaded elements strength losses are tabulated and plotted. Besides, crack patterns of conventional elements and tearing BFRP wrapped elements were also observed. The BFRP wrapped elements and retrofitted elements withstand more axial compressive load than the conventional elements.

Experimental Research on the Effects of Pipe Diameter on Axial Compression Properties of GFRP Tubes Reinforced Concrete Column

Through the axial compression experiment of 9 GFRP tubes reinforced concrete columns, this paper analyzes the failure mode and loading-strain curves under different pipe diameter, and compares bearing capacity between the experimental data with FRP reinforced concrete and the calculated value without GFRP tubes reinforced concrete. he results show that the bearing capacity and ductility of GFRP tubes reinforced concrete column have improved, because of the restriction effect of FRP tubes. The confining ability of FRP tubes on concrete reduced for a certain thickness GFRP tubes constraint concrete short column, while the pipe diameter is increasing.

Experimental Research on the Effects of Reinforcement Ratio on Axial Compression Properties of FRP Reinforced Concrete Column

Through the axial compression experiment of 11 FRP reinforced concrete columns, this paper analyzes the failure mode and loading-strain curves.Comparison between the experimental data with FRP reinforced concrete and the calculated value without FRP reinforced concrete is done. The results show that the reinforcement for the component will increase ductility and ultimate bearing capacity of the composite column, but the increase of reinforcement ratio will also reduce confining ability of FRP tubes.

The Experimental Study on Reinforced Concrete Short-Columns Restrained by Corroded Stirrups

The impact of stirrup corrosion on the constraint of corroded reinforced concrete(CRC) column is an pressing problem that needs to be solved. In this paper, 12 corroded CRC short-columns and 3 uncorroded CRC short-columns with dimension of 150mm×150mm×450mm have been prepared for the axial compression experiment. Through the experiment, the total cross-section stress-strain curves of the short-columns were measured under different degrees of stirrups corrosion, and the effects of corrosion rate of stirrups on the shape of the total cross-section stress-strain curves, bearing capacity, deformation and the mechanical parameters of confined concrete have been investigated. According to the results, the corrosion of stirrups has reduced their section, changed the material quality and damaged the concrete cover, which reduces the constraint to the core concrete; the shape changes of stress-strain curve illustrate that the destructive form of short-columns developed form ductility damage to brittle failure gradually.

Study on the Strength and Deformation of Stirrup Confined Concrete in Cruciform Columns

In order to determine the strength and deformation characteristics of confined concrete under axial compression of cruciform columns, the test results have been obtained for reinforced concrete cruciform columns through axial compression experiment in the study. After analysis and research, the stress-strain curves of confined concrete have been established, the relational expression between the relatively increased value of the peak strain value of confined concrete in cruciform columns and the stirrup characteristic value was proposed, the descending section of the stress-strain curves of confined concrete was studied, and the variation relationship between the strain ductility coefficient of the confined concrete and the stirrup characteristic value was established. The study results will be provided as reference for the structural design and deformation calculation of cruciform columns.

Microscopic Study of Pressure-Transfer Characteristics in the Solid Granule Medium Forming

To reveal the pressure-transfer characteristics of the granular materials in the Solid Granule Medium Forming process, the stainless steel balls with diameter of 1 mm were selected as medium to conduct the axial compression experiment. The particle compression process was simulated by discrete element method, and then the variation law of the microstructure was analyzed from the perspective of force chain. The results showed that: In the gradual compression process of granule medium, its force chains distribution changes from the initial circular shape to the elliptical shape. As the stress increases, the force chains get denser and denser. In addition, the lateral pressure coefficient changes in power law with the compressive stress and it tends to be constant when the internal force chains structure gets stable.