Influence Of Eccentric Loading Research Articles

Experiments and predictive modeling of optimized fiber-reinforced concrete columns having FRP rebars and hoops

This research studies the structural performance of glass fiber-reinforced polymer (glass-FRP) reinforced concrete (RC) columns incorporating glass hybrid fibers (GFC) and steel rebars RC columns having steel hybrid fibers (SFC) using experiments, artificial neural networks (NN), and theoretical modeling. A set of 18 circular concrete columns, each with a diameter of 300 mm and a height of 1200 mm, was constructed and axially loaded to failure. Glass fibers and steel fibers were incorporated to produce hybrid fiber-RC (HFRC). Nine samples were manufactured with glass-FRP reinforcement, while the remaining nine were manufactured with steel reinforcement. According to the findings, the GFC columns had lower axial strengths (ASs) up to 20%, and higher ductility indices up to 26% than the SFC columns. Both GFC and SFC columns showed the same influence of eccentric loading in the form of a decrease in AS. To develop a novel NN model, a database of 275 specimens of glass-FRP-RC columns was gathered from previous studies. To achieve an optimum model, the NN model was calibrated for different numbers of neurons in the hidden layers (HLs). A novel theoretical equation for determining the AS of GFC columns was also suggested. The proposed theoretical and NN models showed average discrepancies of 3.2 and 1.9% from the test results of both GFC and SFC columns.

Study on mechanical behavior and damage process of concrete with initial damage under eccentric load

In order to analyze the influence of eccentric load on mechanical properties and damage process of concrete with initial damage, the eccentric load compression tests of concrete under different confining pressures were carried out with the help of PFC particle flow program. The results show that: the eccentric load does not change the relationship between peak stress, crack initiation stress and confining pressure of concrete under uniform load, but decrease the value of them. The peak stress increasing coefficient under uniform load is higher than that under eccentric load, and the peak stress increasing coefficient increases in a linear function with the confining pressure, and the increasing rate is approximately the same. Under uniaxial compression of eccentric load, a type I shear crack approximately parallel to the loading direction is formed, while under biaxial compression, a bending type shear crack with the lower tip of the initial crack as the inflection point is formed. The number of microcracks in concrete under uniform load and eccentric load can be divided into three stages: the calm period at the initial loading stage, the pre-peak expansion period from crack initiation point to peak point, and the rapid increase period after the peak.

偏心荷重が超高強度コンクリートの圧縮強度試験結果に及ぼす影響

This paper deals with the influence of the eccentric loading in the compressive strength test of high-strength concrete. In the experiment, five kinds of concretes (water binder ratio is 65% to 20%) were examined. The range of eccentric distance is 0 mm to 9 mm. Conclusions are as follows. (1) The influence of eccentric loading becomes large as concrete becomes more high-strength. (2) The experimental result of (1) can be presumed based on vertical strain of specimen. (3) The compressive strength test result in the tolerance level of JIS A 1108(within 1mm) becomes almost equivalent. (4) Under eccentric loading, the horizontal strain of the upper part of specimen became small. This result has suggested increasing the restraint of the upper part of specimen under eccentric loading.

Behaviour of FRP wrapped normal strength concrete columns under eccentric loading

Eccentric loads are common for columns in buildings and other types of structures. Columns that are in the border of buildings, especially corner columns and columns near opening are usually subject to a combination of axial load and bending moment, thus creating an equivalent eccentric load. Fibre Reinforced Polymers have been used in strengthening/retrofitting columns and other types of elements. The results by and large are satisfactory. Most of the research studies undertaken in strengthening columns are based on concentrically loaded columns. In effect, the behaviour of FRP wrapped columns under the influence of eccentric loading is less known compared to concentrically loaded columns. This paper presents results of testing six normal strength concrete columns under eccentric loading. The columns are wrapped with different number of layers of FRP. Results show that wrapping a column with an adequate number of FRP layers will result in higher strength, ductility and energy absorption than a column reinforced with steel bars.