الفهرس 
LITERATURE SURVEYOnly 14 pages are availabe for public view
 |  | from | 230 |  |  |
| | | from | 230 | | |
Abstract
Based on the presented experimental results, presented numerical results and the prediction of columns, ultimate loads and moment capacities according to the ECP code, ACI code and proposed prediction the following conclusions can be drawn: [1] High performance concrete columns have better cracking behavior than that of normal and high strength concrete columns which is evidenced by more multiple micro tension cracks leading to higher cracking, ultimate loads, and energy absorption. [2] As the load eccentricity decreases the efficiency of using high performance concrete increases, where the difference in ultimate load between high performance concrete columns and normal strength concrete ones are ranged from 7% to 55% according to eccentricity-to-depth ratio. [3] The high strength concrete column has less ductility than normal and high performance concrete columns. 189 [4] Eccentricity-to-depth ratio (e/t) is a very significant parameter on the column failure mode, where, for e/t of 0.2 the compression failure is occurred while for e/t of 0.5 and 0.8 the tension failure was achieved. [5] Increasing longitudinal steel ratio is very effective parameter in enhancement the load capacity and ductility up to 2% where increasing longitudinal steel ratio from 1.4% to 2% leads to increase the load capacity by a value ranged from 39% to 54% while increasing reinforcement ratio from 2% to 3.5% leads to a little gain in load capacity by a value ranged only from 6% to 14% with no gain in ductility. [6] Strengthening high performance concrete column of e/t=o.5 by spiral CFRP sheets wrapping and near surface mounted CFRP strips (NSM) increase load capacity by 22% and 37% respectively. [7] from economic point of view, using spiral CFRP sheet is the optimum technique for strengthening high performance concrete eccentric column, where it has more preferable failure mode and also, its total cost is less than the near surface technique with decrease in efficiency of strengthening by only about 11% compared with the other technique. [8] The numerical results have a good agreement with the experimental results. [9] The prediction of eccentric load by ACI code is more conservative than that by ECP code especially for higher reinforcement ratio. 190 [10] For specimens with eccentric–to-section width ratio (e/t) equals to 0.2, the experimental and numerical results of ultimate load is higher than ECP code by 19.54% to 29.5% and ACI code by 36.7% to 43.5% respectively according to different reinforcement ratio respectively. [11] For specimens which have eccentricity to section width ratio (e/t) equals to or less than 0.4, the results of numerical ultimate load for specimens that have strength of concrete 52 MPa are higher than prediction of load by ECP code, while that specimens which have eccentricity to section width ratio (e/t) are higher than 0.4, the results of numerical ultimate load are lesser than prediction of load by ECP code [12] For specimens which have eccentricity to section width ratio (e/t) equal to or less than 0.4, the results of numerical ultimate load for specimens that have strength of concrete 52 MPa are higher than prediction of load by ACI code, while that specimens which have eccentricity to section width ratio (e/t) are higher than 0.4, the results of numerical ultimate load are lesser than prediction of load by ACI code except the specimens with e/t equal to 0.5,0.6 and 0.7 with bigger longitudinal steel ratio (3.5%,4% and 4.5%). [13] Accurate prediction for capacity of eccentric section is proposed to modify the ECP code prediction of eccentric column and the proposed prediction has good agreement with the experimental and the numerical results.