Papers by Keyword: Concrete Column

Abstract: Currently there are different techniques of soil improvement. One of them is the gravel columns that is one of the most popular and profitable techniques for soil improvement. This method of breeding increases the physical and mechanical properties of the soils. However, it has limitations, because part of the aggregates in non-specific areas can generate settlement that affects the structure. In this study, it reduces the settlement of the gravel column by making a change in a certain percentage in its structure by a concrete that is not reinforced. Different heights of the concrete are visualized, in addition to having different variants such as columns that are next to the base, as well as the columns that are on the sandy ground. The research was carried out with the simple compression machine with the concept of unit cell. The yield of the hybrid columns (gravel and concrete) had a better yield which was 20% compared to the traditional gravel columns.

Abstract: An experimental investigation on square and circular high-strength concrete short columns confined with aramid fiber-reinforced polymer (AFRP) sheets was conducted in this study. Fiber Bragg grating sensors have been applied successfully in monitoring of the strains of the AFRP-confined square and circular concrete columns. The experimental results demonstrate that two types of axial force-strain curves were observed depending on the form of the column. Results show fiber Bragg grating sensors have good repeatability and the ultimate load of the circular concrete column is larger than that of the square concrete column. The interlaminar strains of AFRP and high-strength concrete have also been attained. It helps to analyze the constraint effect of the concrete column and compute the ultimate load of the square and circular concrete column.

Abstract: Several numbers of strength models of FRP-confined circular concrete columns have been published by several researchers. In this study, strength models were proposed based on experimental data. Nine existing FRP-confined strength models of column confinement were reviewed in this study and two forms of strength models of FRP-confined circular concrete columns were proposed. The models were proposed based on different number of experimental data collected from literature. Based on the number of experimental data, i.e. 64-, 106-, 156- and 192-, the strength models were developed. The performance of the existing and the proposed strength models were evaluated and compared. The evaluation results showed that the strength models proposed based on 192-data had the best performance among other models proposed with smaller number of data. It was also shown that the proposed strength models had better performance than the existing strength models.

Abstract: Paper deals with the assessment of the fire safety of composite steel and concrete column as the selected structural element of 30 storey building. The effects of the fire are considered in accordance with the standard EN 1994-1-2. The probability of the column collapse is calculated. The deterministic and probability analysis of the fire resistance of the composite column is considered. The MC simulation is realized for 10⁶ samples of the input data. The sensitivity analysis of the various input parameters shows the significant influence of the action effect and material uncertainties.

Abstract: The behavior of the bearing capacity of the reinforced concrete columns confined with basalt fiber reinforced plastic sheet (BFRP) under axial compression is analyzed by the finite element method, and obtain the ultimate compressive strength and stress distribution of the BFRP. The analysis results show that the simulation results agree well with the experimental results, the strength and ductility of the BFRP reinforced concrete columns are improved obviously. The ratio of the strength test values and simulation values is between 0.91~1.14, the error is within an acceptable range. Then based on the strength of FRP confined concrete columns model, the test values are compared with those of the strength model calculation values, the ratio of the simulation values and calculated values is ​​between 0.94 to 1.03,that means the simulation values are credible. The mechanical properties of the BFRP reinforced concrete column are improved significantly.

Abstract: To study the durability of reinforced concrete structures under coupling effect of load and environmental, an analog device is developed. Device includes sustained loading, accelerated environmental corrosion and measuring systems. The load applied to the column is real-time monitored by the pressure sensor and compensated according to the stiffness degradation and stress relaxation of column due to the rebar corrosion. Electrode is placed in the column so that the arrangement of the measuring instrument is not restricted. Device successfully realizes monitoring the time-varying mechanical performance degradation of reinforced concrete under the coupling effect of load and environment.

Abstract: This paper deals with the behavior of concrete columns actuated by SMA wires winding around the column’s cylindrical surface, when the concrete column are constrained and driven in circumferential direction by the SMA wires, the column’s ultimate bearing capacity and axial deformation are mainly studied. Both theoretical research and finite element simulation are carried out. The results indicate that, the SMA’s limited recovery in reverse transformation by heating can generate circumferential prestress, which will improve the concrete column’s ultimate bearing capacity and control its deformation, so as to realize the concrete column’s recovery strengthening.

Abstract: In order to maintain the existing concrete structures in a safe and usable state, an overall maintenance management is necessary regarding structure aging from quality management of new construction. Thus, non-destructive testing is needed to estimate the structure damage, defect, or proper construction without damaging the structure. In U.S., there is a standard for non-destructive test (ACI 228.2R-98), and also in Japan, the non-destructive test method and compressive strength estimation manual was prepared by the Architectural Institute of Japan in 1983, and there are active researches in the ground field, but it lacks verification in architecture field. Thus, in this study, a technique that can estimate the depth of concrete column member using the Impact Echo method which is one of the non-destructive test methods shall be reviewed and evaluated for applicability to the architecture field. The specimen was mixed with design strength of 30MPa. The equipment used in testing is Freedom Date Pc Platform Win.TFS 2.5.2 by company Olson of U.S., and the experiment involved leveling the top surface of the concrete member, installing the equipment and applying impact 9 times, and taking the average of the reverberation values obtained. The estimated average depth of concrete column member using Impact Echo method was 304mm for IEC-300, 398mm for IEC-400, and 484mm for IEC-500, and the relative error rate compared to the actual size was 1%~3%. Through this study, the applicability of estimation of depth in concrete column members using impact echo method could be confirmed.

Abstract: t is essential to study the performance of reinforced concrete short column. In this paper, the main reinforcements and hoopings in short columns were replaced by C-BAR reinforcements, the regularity of reinforcing bar replaced by C-BAR reinforcements was summarized. The results show that the axial compression bearing capacity of concrete short column is increased.

Abstract: Concrete column in engineering need to increase the bearing capacity for various reasons, and requires the column section not to increase. In order to solve this problem, we start two tests of concrete column reinforced hoop and steel plate hoop reinforcement to propose the formula for calculating the bearing capacity, which can be used for reference in the practical engineering.