Feng Xiao

• PhD
• Professor (Associate) at Nanjing University of Science and Technology

The objectives of this research are (a) to establish a structural health monitoring system for bridge safety evaluation that is suitable for cold, remote regions and (b) to identify the bridge responses under variations in temperature. To achieve this, fiber optic sensors with temperature compensation were selected that were suitable for cold regio...

A method to identify optimal strain sensor placement for examining structural static responses is presented. The method is based on the use of numerical optimization. Based on an assumed set of applied static forces, the optimal sensor placement can be obtained, and the measured strains can be used to provide the information needed to describe the...

Optimization-based damage identification of large-scale space truss structures is challenging because with increasing degrees of freedom for the structures, the objective function becomes complex that is difficult to converge. To solve this issue, this study introduces a stiffness separation method for damage identification of large-scale space tru...

Anchor bolts, such as rock bolts and concrete anchors, are widely used in civil, geotechnical, and mining engineering for anchorage and ground support. They are used in retaining walls, dry docks, dams, mines, and prestressed concrete structures. Evaluating the grouting condition of anchor bolts is essential to ensure the safety of these applicatio...

The inversion of a high-dimensional stiffness matrix with unknown parameters is time-consuming. In this study, a stiffness separation method is used to solve the large-scale matrix inversion problem. Substructures are isolated from the overall structure by mapping the substructure-related matrix, and the solvable equilibrium equations for the subst...

Damage detection in bridge structures has always been challenging, particularly for long-span bridges with complex structural forms. In this study, a partial-model-based damage detection method was proposed for the damage identification of long-span steel truss bridges. The proposed method employs partial models to estimate the parameters using the...

This paper presents a study to accurately evaluate defects in concrete decks using ultrasonic pulse-echo signals. A reinforced concrete deck with void defects was designed and evaluated for validation, and a commercial ultrasonic pulse-echo (UPE) device was used to obtain the 2D images of the void defect inside the deck. The UPE image is based on t...

Identifying the parameters of multispan rigid frames is challenging because of their complex structures and large computational workloads. This paper presents a stiffness separation method for the static response parameter identification of multispan rigid frames. The stiffness separation method segments the global stiffness matrix of the overall s...

This paper presents a method to identify the damages in frame structures with slender beams. This method adjusts the parameters of the structure to match the analytical and the measured displacements. The effect of transverse shear deformation on the nodal analytical displacement is analyzed, and the parameter identification of frame structures wit...

Shear deformation plays an important role in certain structures, and neglecting shear deformation can affect the accuracy of structural response. This paper proposes a non-destructive damage evaluation method that considers shear deformation, based on static response, for identifying corrosion in beam-like structures. The influence of shear deforma...

A damage identification methodology considering shear deformation was presented in this paper to identify damage to semi-rigid frames with slender beams. On the basis of the successful identification of structural joint damage, the combined joint and member damage of the structure was identified. The objective function was formulated to minimize th...

Quantifying vehicle-bridge interaction mechanism is critical for bridge safety design, transportation weight control, condition assessments in maintenance, and structural health monitoring. In this paper, the stochastic non-stationary characteristics of a bridge under vehicle-bridge interaction are investigated. The response of the bridge under the...

This paper presents a parameter-identification method for rod structures with different connections. In this method, the parameters of the structure are adjusted to match its analytical and measured displacements. The damage identification for truss structure and rigid frame were investigated. Previous studies often considered the cross-sectional a...

The viscoelastic property of pile-soil interactions is modeled by fractional derivative method and is used to characterize the structural dynamics of pile and rheological behavior of a thawing frozen soil. A study of the thawing frozen soil impacts on pile structure’s dynamic characteristic is carried out. The frequency spectrum analysis and empiri...

Technology that measures bridge responses when a vehicle is crossing over it for structural health monitoring has been under development for approximately a decade. Most of the proposed methods are based on identification of the dynamic characteristics of a bridge such as the natural frequency, the mode shapes, and the damping. Specifically, many t...

This article presents a new protection device using aluminum foam to enhance the impact resistance of bridge columns. First, the protection device is designed according to the characteristics of aluminum foam material. The geometric configuration and structure of the device are described. Second, the impact performance of bridge column is analyzed,...

Health condition monitoring through comprehensive monitoring, incipient fault diagnosis, and the prediction of impending faults allows for the promotion of the long-term performance of wind turbines, particularly those in harsh environments such as cold regions. The condition monitoring of wind turbines is characterized by the difficulties associat...

In this paper, we investigate vehicle–bridge interactions and propose a new method for assessing bridge conditions based on nonlinear vibration analysis. A vehicle model is presented, and the dynamic load on the bridge is quantified based on bridge road roughness. The vibration of a river bridge under a moving vehicle is recorded and analyzed. The...

Strain gage sensors have been used to evaluate the local behavior of structures; however, there are limited studies for its application in bridge dynamic feature identification. In this study, fiber Bragg grating strain gages were installed on the lower chord members of a bridge, and dynamic features were identified successfully using strain gage r...

In this study, a distributed optical fiber sensing technique based on Brillouin optical time-domain analysis (BOTDA) is used to construct a complete bridge health monitoring system by continuously laying distributed sensing fiber lines in a steel box girder. The bridge scaffolding dismantling process is monitored to study the variation of the strai...

The piers of girder bridges have a very important role on the safety of the structural system to earthquakes. This paper addresses the seismic fragility of double-column (DC) bridge piers by focusing on the influence of the straining beams and the direction of seismic waves. The seismic capacity of eight DC piers with different number and position...

A novel technique to identify bridge damage using genetic algorithms and simulated annealing is proposed in this article. In the proposed method, the cross-sectional area of the damaged member is set as a variable that can be updated. An objective function was investigated to estimate the current condition of the damaged members. This function is t...

Purpose and Methods This study investigates the characteristics of bridge–abutment interaction based on the vibration spectra of the recorded vibration responses of the abutment, which characterize the vibration transformation from the bridge to the abutment. To this aim, the abutment response excited by a moving truck on the bridge is used to eval...

This paper presents an analysis of fluid-induced vibrations of an operational wind turbine. The experimental data and FFT analysis show that under the effects of strong wind load, the wind turbine system exhibits certain complicated vibrations. The advanced spectrum analysis and phase space analysis reveal the complicated patterns of fluid-induced...

Purpose and Methods This research studies the nonlinear dynamic feature of the Chulitna river bridge in Alaska USA. The acceleration response of the bridge under moving truck loads are evaluated for dynamic invariants. The Fourier spectrum of a free-decay response (after the vehicle passes) exhibits a salient line spectrum, which is correlated to c...

As all bridges get deteriorated over time, structural health monitoring of these structures has become very important for the damage identification and maintenance work. Evaluating a bridge's health condition requires the testing of a variety of physical quantities including bridge dynamic responses and the evaluation of the functions of varied bri...

This paper investigated dynamical interactions between pile and frozen ground by using the ensemble empirical mode decomposition (EEMD) method. Unlike the conventional empirical mode decomposition (EMD) method, EEMD is found to be able to separate the mode patterns of pile response signals of different scales without causing mode mixing. The identi...

In bridge health monitoring, tiltmeters have been used for measuring rotation and curvature; however, their application in dynamic parameter identification has been lacking. This study installed fiber Bragg grating (FBG) tiltmeters on the bearings of a bridge and monitored the dynamic rotational angle. The dynamic features, including natural freque...

Most of the man-made structures in cold regions could expose in seasonally frozen conditions which could have significant impact on the soil-pile systems of structures. Little research has been conducted to investigate the thawed frozen soil effects on the dynamic performance of pile structures. An experimental investigation of the thawed frozen so...

Quantifying the non-stationary properties of bridge under passing vehicle has been an important topic in structural health monitoring of bridge. There are many methods of time–frequency representation used for the study of dynamics of bridge under passing vehicle, including spectrogram, wavelet, Hilbert–Huang transform, and so on. This article uses...

This paper describes a methodology used to evaluate the structural condition of a bridge in a remote area of Alaska in the United States. The objective was to develop a Structural Health Monitoring (SHM) program to improve bridge safety and asset management. The idea is to evaluate the structural integrity and serviceability of the bridge and gathe...

The Chulitna River Bridge is a 790-ft five girder, five-span steel bridge on the Parks Highway between Fairbanks and Anchorage, Alaska. This bridge was built in 1970 and widened in 1993. Under the no-live load condition, five support bearings are not in contact. Heavily loaded trucks often travel across this bridge to the oil fields in Prudhoe Bay,...

This research present a multi-direction bridge finite element model updating method based on the static and dynamic test. A fiber optics structural health monitoring system was installed on the bridge site and 73 fiber optic sensors captured the static and dynamic data in local-level. A portable accelerometer system was used to record the ambient l...

This paper aims to explore fundamental characteristics of bridge vibration spectra to potentially evaluate soil-abutment interactions and changes in abutment earth pressures. To this aim, the bridge response to the excitation of an approaching vehicle on road is utilized to evaluate the transmissibility of the road-soil-abutment-bridge (r-s-a-b) pa...

The objective of this research is to improve the safety of bridge structures in the state of Alaska through implementation of innovative structural health monitoring (SHM) technologies. The idea is to evaluate structural integrity and serviceability, and to provide reliable information for changing structural response, etc. of monitored bridges. As...

A set of dynamic field tests were conducted on the Chulitna River Bridge recently. The Chulitna River Bridge, built in 1970, is located at Historic Mile Post 133 on the Parks Highway between Fairbanks and Anchorage, Alaska. Ambient free-decay response approach is used to estimate the dynamic properties of the bridge. Stationary and dynamic tests on...

In August of 2012, Alaska University Transportation Center (AUTC) was requested by the Alaska Department of Transportation & Public Facilities (AKDOT & PF) to install the structural health monitoring system on the Chulitna River Bridge along the Parks Highway outside of Trapper Creek, AK. The objective of this study is to provide important informat...