Identification of suitable methods for static pile load capacity and recommendation for BNBC 2020

Area of Science:

• Geotechnical Engineering
• Structural Engineering

Background:

• Accurate pile capacity determination is crucial for foundation design.
• Existing theoretical methods require validation against empirical data for diverse soil conditions.
• The Bangladesh National Building Code (BNBC) 2020 provides guidelines for pile capacity estimation.

Purpose of the Study:

• To compare theoretical pile capacity prediction methods with static pile load test results.
• To identify the most effective methods for various soil and pile types.
• To propose potential modifications for BNBC 2020 guidelines.

Main Methods:

• Collected data from six projects involving precast and cast-in-situ piles.
• Performed theoretical analyses using BNBC 2020 (α-method, β-method), SPT-based BNBC 2020, and literature methods (Meyerhof, Shioi Fukui).
• Interpreted static load test data using eight evaluation methods per ASTM D1143 and performed statistical analysis (MAPE, Bias Factor, COV).

Main Results:

• For clay soils, SPT-based equations from Shioi & Fukui (skin friction) and Meyerhof (end bearing) demonstrated lower variation compared to actual pile capacity.
• For sandy, silty, and layered soils without clay, the SPT-based equations within BNBC 2020 were found to be appropriate.
• Statistical analysis identified varying degrees of predictive accuracy among the evaluated methods.

Conclusions:

• The Shioi & Fukui and Meyerhof equations offer viable alternatives for clay soil pile capacity estimation in future BNBC revisions.
• Current BNBC 2020 SPT-based methods are suitable for non-clayey soil conditions.
• Empirical validation is essential for refining theoretical models in geotechnical engineering practice.