Strength Of Transverse Reinforcement Research Articles

EXPERIMENTAL RESPONSES OF HIGH-STRENGTH KC COLUMN WITH LARGE AXIAL LOAD

A kernel-confined (KC) column, which a reinforced-concrete (RC) column moves partial longitudinal reinforcements from conventionally placed on outer periphery of section to inner kernel-confined region (KC bar), was concerned in this paper. This paper mainly intended to investigate seismic behaviors of the KC column with large axial loads. There are six sets of high-strength RC column specimens with 600 mm × 600 mm in section to be conducted. Their design strength of concrete was 70 MPa, and steel grades of SD550W and SD790 were designed as the longitudinal and transverse reinforcements, respectively. The number and location of the KC bar and the number and strength of transverse reinforcement are key study parameters. Test results indicated that for all specimens, including KC columns, the testing maximum moments were larger than the computed moment from ACI model and their average value of overstrength ratio of the testing to the computed was 1.25. In addition, the strength obtained from the XTRACT software had a better prediction with an average error of 0.99. Based on test deformation results for all specimens, the amount of the confined reinforcement per ACI 318-19 with an axial load of 0.5fc’Ag, can provide 3% radian of inter-story drift angle capacity for the high-strength RC column.

Effect of Configuration and Yield Strength of Transverse Reinforcement on Lateral Confinement of RC Columns

In general, the lateral confinement capacity of RC columns is influenced by the strength and configuration of transverse reinforcement. In this study, performed antisymmetric flexural moment experiments that simulated seismic loads, with the configuration and yield strength of the transverse reinforcement of RC square columns as main variables. The eight specimens were square cross-sections measuring 250 × 250 mm, and the lateral confinement effect in relation to main variables was examined by inducing flexural failure in the plastic hinge zone under a shear span-to-depth ratio (a/D) of 3.0. Transverse reinforcements comprised a square and octagonal S-series and tie-based H-series. The yield strengths of the transverse reinforcements were 453 MPa and 1053 MPa, respectively. Compared to the H-series, the S-series, whose configuration of transverse reinforcement is closer to a circular form, exhibited more prominent ductile behavior after flexural yield with increasing yield strength of transverse reinforcement, which indicates greater lateral confinement.

Structural behaviour of prestressed concrete beams with high-strength stirrups

Many studies related to high-strength concrete material have been conducted, but relatively few studies have considered high-strength steel reinforcement. Four current design codes – ACI 318-14, Eurocode 2, CSA A23.3-04, and JSCE-07 – limit the yield strength of transverse reinforcement to control diagonal crack width, and to ensure yielding of transverse reinforcement prior to brittle failure mode. ACI, Eurocode 2 and CSA A23.3-04 limit the yield strength of transverse reinforcement to 420, 600, and 500 MPa, respectively; while JSCE-07 limits the yield strength to 800 MPa, when the compressive strength of concrete is higher than 60 MPa. The implementation of high-strength transverse reinforcement in prestressed concrete (PSC) and reinforced concrete (RC) beams has been determined in this study. A total of 16 beams were strengthened using higher yield strength stirrups than the code limitations, and were monotonically loaded to failure. All the beams were designed to experience shear failure prior to flexural failure. Most of the test results showed yielding of the stirrups, and narrower crack width than the code limitations even though the specimens were strengthened with higher than 420 MPa stirrups. The test results imply the feasibility of using high-strength stirrups for PSC beams with regard to serviceability.

ДЕФОРМИРОВАНИЕ ЦЕНТРАЛЬНО СЖАТЫХ ЖЕЛЕЗОБЕТОННЫХ КОЛОНН ИЗ БЕТОНА С ДОБАВЛЕНИЕМ КРУПНОГО ЗАПОЛНИТЕЛЯ ИЗ БЕТОННОГО ЩЕБНЯ

The article presents results of experimental studies of centrally compressed reinforced concrete columns with the addition of concrete rubble as coarse aggregate. Previous studies shows that recycled concrete in the form of crushed concrete rubble obtained from construction waste is an environmentally friendly alternative to traditional coarse aggregate for the manufacture of load-bearing structures. Currently, the scientific literature has a limited amount of information about the calculation methods to be used for the design of reinforced concrete columns with the addition of concrete rubble as coarse aggregate. In this paper, the experimental data on the physicomechanical properties of concrete available in the foreign and domestic literature are summarized. In addition, the deformation features of reinforced concrete columns are highlighted to substantiate the initial premises, hypotheses and possible limitations when developing methods for calculating centrally and eccentrically compressed elements from the specified concrete. Researches are analyzed related to the effect of different content of recycled concrete aggregate in the concrete, the number of longitudinal steel reinforcement in the cross section of the element and its yield strength, pitch and yield strength of transverse reinforcement on the deformability and bearing capacity of concrete columns with the addition of coarse aggregate from concrete rubble. The use of such concrete for the manufacture of centrally and eccentrically compressed concrete columns leads to an insignificant decrease in their bearing capacity. This indicates the possibility of recycling a significant amount of concrete rubble resulting from the processing of reinforced concrete structures destroyed during the demolition of buildings; it allows to attribute this technology to “green building”.

Structural Behavior of RC Cylinders Confined with High Strength Transverse Reinforcement

The number of high-rise reinforced concrete (RC) buildings is steadily increasing since 1980’s. The use of high strength concrete is indispensible for high-rise RC construction to ensure sufficient strength of the structure. The effect of high strength concrete can be significantly improved by the use of high strength and large size reinforcing bars. The yield strength of transverse reinforcement is limited in the current design codes to prevent possible sudden concrete failure due to over reinforcement. This paper presents the effects of the yield strength of transverse reinforcement and compressive strength of concrete on the structural behavior of reinforced concrete cylinders. Two parameters were considered in this investigation: compressive strength of concrete and the yield strength of transverse reinforcement (472MPa, 880MPa, and 1,430 MPa). Analytical and experimental results indicated that the structural behavior of RC cylinders confined with high strength transverse reinforcement is strongly influenced by compressive strength of concrete.

A fuzzy logic approach to predict seismic ductility and shear strength of reinforced concrete elements

Structures require ductility to withstand severe earthquake-induced loads and remain standing. A new method for modelling seismic displacement ductility is proposed here, in which a fuzzy inference system is utilized to include the uncertainty in the parameters that influence this behaviour. The proposed model is also used to determine the lateral shear strength, a vital parameter in seismic design. Experimental data are presented for beams subjected to cyclic loading. Numerous input design parameters were considered including the beam width/depth ratio, the longitudinal reinforcement ratio, the bottom/top reinforcement ratio, the concrete compressive strength, the transverse reinforcement strength, and the shear span-to-depth ratio. Output parameters included the displacement ductility and lateral shear strength. The proposed model can predict the outputs successfully with an error of ±20%, but is more effective in predicting shear strength than displacement ductility.

Ductility of High-Performance Concrete Beams with High-Strength Lateral Reinforcement

The aim of this study was to investigate the flexural behavior of high workability, high-performance concrete (HPC) beams with high-strength transverse reinforcement under static load. A total of 21 beam specimens were fabricated in this study: 7 were normal concrete beams, and the remainder were HPC beams. The parameters included concrete strength, amount of tension reinforcement, amount of compression reinforcement, amount of transverse reinforcement, and strength of transverse reinforcement. Results show that HPC beams have slightly higher strengths than normal concrete beams. In addition, an increase in tension reinforcement will increase the strength but decrease the ductility of the beams. An increase of compression steel and concrete strength will increase the ductility of the beams effectively. HPC beams show better ductility than normal concrete beams. HPC beams also have better crack control than normal concrete beams. Beams with high-strength shear reinforcement exhibit the same crack control ability as beams with normal strength shear reinforcement.