Evaluasi perilaku pilecap akibat perbedaan daya dukung tiang dalam satu tipe pondasi dengan Compatible Stress Field Method (studi kasus pondasi square pile Gedung X, Bangka Belitung)

Abstract

An anomaly in the load-bearing capacity was observed at one of the foundation points of Building X in Bangka Belitung. One pile did not reach the final set, while two other piles did. The term "final set" refers to the acceptance of a pile’s load-bearing capacity, indicated by the amount of deformation resulting from the pile driving process and the hammer energy applied. The discrepancy in pile load capacities could affect the pile cap. Therefore, a study was conducted to analyze the behavior of the pile cap, focusing on concrete stress, reinforcement forces, and settlement. The research employed the Compatible Stress Field Method (CSFM) and used the licensed software Ideastatica for modeling. The square pile foundation was modeled with spring constants derived from the ratio of pile capacity to settlement. The load-bearing capacity of piles that reached the final set was calculated using the modified ENR method, while those failing to meet the final set were assessed using PDA tests. The superstructure load was modeled as a uniform load. Material properties were based on Eurocode equations, and reinforcement material data were obtained from previous studies. The maximum concrete stress was 3 MPa in Test Model A and 7.4 MPa in Model B. The maximum reinforcement force was 3.1 kN in Model A and 11.1 kN in Model B. Settlement in Model A was 0.1 mm and 3.2 mm in Model B. Both models remained within safe limits. The pile cap behavior under anomalous conditions significantly differed from the normal condition.