Assessment of load capacity of piles and conclusion of a new criterion using static load tests

In this study, a comprehensive evaluation of 27 field tests carried out on different piles driven in various parts of Iraq. This evaluation is made in terms of the pile bearing capacity of each pile, using nine methods. These methods are (Davison offset limit, Chin konder, Brinch Hansen 80%, Brinch Hansen 90%, De court, De Beer, Vander Veen, Fuller&Hoy and Butler&Hoy). The evaluation has shown that De Beer, Chin kondeer, and Vanderveen methods are the best methods because the maximum bearing capacity obtained by these methods is associated with a low pile settlement, although Vander Veen method is time-consuming. Fuller&Hoy and Davison methods are very close and give good results, the maximum bearing capacity obtained by these two methods give high pile settlement, leading to structure failure, especially for structures subjected to loading and unloading. Brinch Hansen 90% and Butler&Hoy methods are suitable methods because they give a good and acceptable bearing capacity with very small pile settlement. As for Brinch Hansen 80% and De Beer methods, they provide high bearing capacity than the failure load. They can be used by multiplying the resulting values by 0.85 to get the maximum bearing capacity of the pile. The study shows that the ratio of 10% after comparing it with results is a bit exaggerating, and 4% of pile diameter can be used as a criterion to find the ultimate load.