All the specimens were cast in commercial concrete。 The concrete class was C40, and its actual compressive strength on cubes with dimensions of 150 × 150 × 150 mm was measured to be 42。3 MPa at 28 days。
All specimens were strengthened longitudinally with six 14-mm-diameter deformed bars and 8-mm-diameter smooth stir- rups。 According to the building code requirements for structural concrete and commentary (ACI 318-11), the reinforcement ratio is 1。03% in this test, which is reasonable。 Steel tension tests were carried out, and the yield stress, tensile strength, and elongation ratio of the steel bars were determined。 The detailed parameters are listed in Table 2。
Textile
The textile is a mixture of carbon and alkali-free glass yarns with a 10-mm grid spacing。 The carbon yarns were used to bear load in the weft, while the glass yarns, which cannot bear load, were used in the warp。 The specific details of the textile are provided in Fig。 2。 The mechanical properties and geometric parameters of the fiber yarns of the textiles, which were provided by the manufacturer, are shown in Table 3。 According to the method proposed by Yin et al。 (2014, 2015), the effective sectional area of the grid is 0。45 mm2。
Fine-Grain Concrete
The mix proportion of the fine-grain concrete used in the matrix of the TRC is shown in Table 4, and the real compressive strength of the high-performance concrete was 52。8 MPa after 28 days。
Load Method and Experimental Content
An mechanical testing and simulation (MTS) electrohydraulic servo-loading system (Hangzhou meters of Mechanical and Elec- tronic Control Engineering, Hangzhou, China) was used for load- ing in this test。 A 50-t level actuator was used to apply the horizontal load, and a hydraulic jack with a cross beam was used to apply the vertical load。 The cross beam was connected with the ground base through two screw rods, and the connecting part is a rotatable ball hinge。 Furthermore, the upper end of the column and the cross beam were fixed by a U-hoop to ensure that the beam keeps still when the specimen has a larger displacement。 The load- ing diagram and test installation are shown in Figs。 3 and 4。 A static data collector was used as the collecting device。 The crack width was obtained by using a DJCK-2 crevice width finder (Beijing Earth Long Science and Technology, Beijing) with an accuracy of 0。02 mm。
© ASCE 04016231-3 J。 Struct。 Eng。
Table 3。 Mechanical Properties and Geometric Parameters of Fiber Yarns of Textile
Fiber type Number of filaments per yarn Filament tensile strength (MPa) Filament elastic modulus (GPa) Filament ultimate strain (%) Yarn tex (g=km) Yarn density (g=cm3 )
Toray carbon (T700S) 12k 4,660 231 2。0 801 1。78
E-glass 4k 3,200 65 4。5 600 2。58
Note: Effective sectional area of the grid is 0。45 mm2 (Yin et al。 2014, 2016)。
Table 4。 Fine-Grained Concrete Mix
Component
Material content (kg · m−3)
Portland cement PII 52。5R