## 4 Conclusions  
The main objective of this study was to find a reliable estimation of the \(E_{c}\) in the installed bored pile. Two full-scale maintained a static loads test on instrumented bored-piles had been conducted in Kuala Lumpur, Malaysia to obtain a reliable range for ultimate skin friction with SPT-N value (i.e., blow counts) alteration. The effects of geologically weak zones through the layered soil ground conditions in crucial parameter-design changing such as elastic concrete modulus and strain-stress along the piles have also been researched. The details of the conclusion are as follows. * Distribution of concrete modulus has been measured from the stress-strain behavior of tested piles and using back analysis. In BP# 1, along with the pile, the \(E_{c}\) value is almost constant at 25 kN/mm\({}^{2}\), however, this value is between 30 and 45 kN/mm\({}^{2}\) in BP# 2. This has indicated that the applied stress is the dominant factor in \(E_{c}\) alteration because of the various soil reaction systems responding to the stresses released from the pile. The maximum change has been measured at the pile's head where the maximum stresses have been recorded, in contrast, \(E_{c}\) variation at the pile's toe is negligible since the least stresses have been applied in the pile base. The stresses of the pile have been declined by the depth because the skin friction of the pile has carried a large portion of applied load in the pile. Maximum permanent (plastic) deformations of 24.63 mm and 19.54 mm have been measured in the pile head for BP# 1 & BP# 2 correspondent to applied stresses of 17305 kPa (\(p\) = 44306 kN) and 16430 kPa (\(p\) = 12905 kN). The pile top settlement has been rebounded to a residual value of 2.4 mm and 8.55 mm in BP# 1 & BP# 2 after unloading to zero. * The obtained result will be helpful for real-time assessment of bored pile during its service life. However, this should be noted that due to the heterogeneous characteristics of the soil, the measured \(E_{c}\) of the tested soil may vary. Variables such as concrete maturity, piling technology, soil parameters, and groundwater level can have a significant influence on the soil-pile interactions as well as concrete pile characteristics. **Author Contributions:** Data collection and experimental works: H.M., B.K., H.N., Writing, discussion, analysis: H.M., A.S.A.R., and R.N., M.M.A. **Funding:** This research has received funding from Ton Duc Thang University. **Conflicts of Interest:** The authors declare no conflict of interest. List of Abbreviations  
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