Theoretical investigation on axial cyclic performance of monopile in sands using interface constitutive models

Cyclic loads generated by environmental factors,such as winds,waves,and trains,will likely lead to performance degradation in pile foundations,resulting in issues like permanent displacement accumulation and bearing capacity attenuation.This paper presents a semi-analytical solution for predicting the axial cyclic behavior of piles in sands.The solution relies on two enhanced nonlinear load-transfer models considering stress-strain hysteresis and cyclic degradation in the pile-soil interaction.Model parameters are calibrated through cyclic shear tests of the sand-steel interface and laboratory geotechnical testing of sands.A novel aspect involves the meticulous formulation of the shaft loadtransfer function using an interface constitutive model,which inherently inherits the interface model’s advantages,such as capturing hysteresis,hardening,degradation,and particle breakage.The semi-analytical solution is computed numerically using the matrix displacement method,and the calculated values are validated through model tests performed on non-displacement and displacement piles in sands.The results demonstrate that the predicted values show excellent agreement with the measured values for both the static and cyclic responses of piles in sands.The displacement pile response,including factors such as bearing capacity,mobilized shaft resistance,and convergence rate of permanent settlement,exhibit improvements compared to non-displacement piles attributed to the soil squeezing effect.This methodology presents an innovative analytical framework,allowing for integrating cyclic interface models into the theoretical investigation of pile responses.

Novel sensing techniques for full-scale testing of civil structures

Performing full-scale structural testing is an important methodology for researchers and engineers in the civil engineering industry.Full scale testing helps the researchers understand civil infrastructures'loading scenarios,behaviors,and health conditions.It helps the engineers verify,polish,and simplify the structural design and analysis theories.To conduct a full-scale structural testing,sensors are used for data acquisitions.To help structural researchers and engineers get familiar with sensing technologies and select the most effective sensors,this study reviewed and categorized new sensing techniques for full-scale structural testing applications.The researchers of this study categorized sensors used for civil-infrastructure testing into traditional contact sensors and remote sensors based upon their application methodologies,and into cabled sensors and wireless sensors based upon their data communication strategies.The detailed descriptions of wireless sensors and remote sensing techniques and their on-site full-scale applications are presented.