adoi:10.16186/j.cnki.1673-9787.2022110051

Received:2022/11/21

Revised:2023/03/13

Published:2024/03/25

Prediction method of vertical bearing capacity of piles assisted with GBDT algorithm

XU Zhijun，ZHAO Shipeng，WANG Zhengquan，TIAN Jiangtao，ZONG Feilong

College of Civil Engineering，Henan University of Technology，Zhengzhou 450000，Henan，China

Abstract: Objectives In order to study the seismic performance of braced and semi-rigid steel frame structure system， Methods a center-braced steel frame with semi-rigid beam-column joints composed of nested one-side bolts and T-stub was designed. Quasi-static test and finite element numerical simulation were conducted to analyze seismic indicators such as hysteresis， bearing capacity， stiffness degradation， and energy dissipation by observing the entire experimental phenomenon. Results The results show that the failure process of the specimen has gone through three stages： elastic section， plastic section， and failure section. The failure mode of the specimen is mainly the buckling failure of the brace under compression，and the plastic deformation mainly accumulates on the brace system， presenting the characteristics of ductile failure as a whole.After the brace breaks，there is no obvious plastic deformation in the beam-column and T-shaped steel joints，and the steel frame still has a high safety reserve，which conforms to the design principle of “strong joints and weak members.” It indicates that the structure has two lines of seismic resistance. Conclusions The cooperative work of brace and semi-rigid steel frame makes the specimen have high lateral stiffness，horizontal deformation resistance， high bearing capacity， stable hysteretic performance， and excellent energy dissipation capacity.During the test， the mechanical performance of the one-side bolts is not significantly different from that of the ordinary high-strength bolt，and there is no serious relaxation of the preload；it can effectively maintain the bolt preload. Through finite element numerical analysis，it is known that reducing the slenderness ratio of brace can effectively improve the seismic performance of the structure.However，a small slenderness ratio can lead to an increase in the stiffness of the brace and accelerate the damage of other components. Therefore， in order to effectively improve the seismic performance of the structure，it is necessary to consider the ductility of the structure and reduce the slenderness ratio of the brace.

Key words:vertical bearing capacity of piles；gradient boosting decision tree；prediction model；evaluation index；robustness