Weigh-in-motion technology is an effective tool that has been extensively used to monitor traffic on highways. Pavement-based weigh-in-motion systems usually have poor durability and will cause traffic interruption during their installation and maintenance process. The recently developed bridge weigh-in-motion technology provides a more convenient and cost-effective alternative to the pavement-based weigh-in-motion technology. Bridge weigh-in-motion systems can be installed without interrupting the traffic. Also, bridge weigh-in-motion systems have the potential to deliver better accuracy than pavement-based weigh-in-motion systems. Due to these significant advantages, the bridge weigh-in-motion technology has been playing an increasingly important role in bridge health monitoring and overweight truck enforcement, and many studies have been conducted to continuously improve the bridge weigh-in-motion technology. In this review, the common algorithms for bridge weigh-in-motion are discussed in detail, and the typical instrumentation of bridge weigh-in-motion systems is also introduced. Meanwhile, much effort is made to identify the remaining issues in the application of bridge weigh-in-motion technology, and the corresponding future research is proposed.

A finite-element (FE) model of a structure is a highly idealized engineering model that may or may not truly reflect the physical structure. The purpose of model updating is to modify the FE model of a structure in order to obtain better agreement between the numerical and field-measured structure responses. In this paper, a new practical and user-friendly FE model updating method is presented. The new method utilizes the response surface method for the best experimental design of the parameters to be updated based on which numerical analysis can be performed in order to obtain explicit relationships between the structural responses and parameters from the simulation results. The parameters are then be updated using the genetic algorithm (GA) by minimizing an objective function. A numerical example of a simply supported beam has been used to demonstrate the concept. This method has also been applied to the model updating of an existing bridge. Results show that this method works well and achieves reasonab...

Research on detecting structural damage at the earliest possible stage has been an interesting topic for decades. Among them, the vibration-based damage detection method as a global technique is especially pervasive. The present study reviewed the state-of-the-art on the framework of vibration-based damage identification in different levels including the prediction of the remaining useful life of structures and the decision making for proper actions. This framework consists of several major parts including the detection of damage occurrence using response-based methods, building reasonable structural models, selecting damage parameters and constructing objective functions with sensitivity analysis, adopting optimization techniques to solve the problem, predicting the remaining useful life of structures, and making decisions for the next actions. For each part, the commonly used methods were reviewed and the merits and drawbacks were summarized to give recommendations. This framework is aimed to guide the researchers and engineers to implement step by step the structure damage identification using vibration measurements. Finally, the future research work in this field is recommended.

Loess, which primarily consists of wind-transported silt and clay particles, is widely distributed around the world, including the central Asia, central Europe, the northwestern and central United States, Alaska, and South America. The metastable structure of natural loess has resulted in construction delays and catastrophic failures. To explore the potential applications of soil improvement with green materials, this paper presents an experimental study of applying fly ash–based geopolymers for the loess stabilization. Two different precursors are employed to the investigation. It is found that potassium hydroxide renders a higher unconfined compressive strength than sodium hydroxide to the samples when the same fly ash/loess ratio is applied. This agrees with the results of the mechanical properties of the two different geopolymers. With an increasing fly ash/loess ratio, the compressive strength and Young’s modulus increase. The microstructural characterization unveils that a compact and stable...

The dynamic response of moving vehicles on a bridge carries the vibration information of the bridge, which a few researchers have studied to extract the bridge modal properties such as natural frequencies and mode shapes. However, the vehicle response contains not only the frequency characteristics of the bridge and vehicle, but also other information such as the driving-related frequencies and road roughness effects, which makes the extraction difficult. To this end, the present study proposes a method using a specialized test vehicle consisting of a tractor and two following trailers, which can eliminate those effects and more efficiently extract the bridge modal properties. The two trailers towed by the tractor moving along the bridge were used as dynamic response receivers. In order to eliminate the effects previously discussed, the responses of one trailer were subtracted by the responses of the other with a time shift to obtain the residual responses. The residual responses were then processed with the fast Fourier transformation (FFT) and short-time Fourier transformation (STFT) to extract the bridge modal properties. Firstly, a theoretical study was conducted to derive the residual responses of the two trailers in a simplified vehicle-bridge coupled (VBC) system and extract the bridge mode shape squares (MSS) by applying the STFT. Then, numerical studies were conducted to demonstrate and verify the proposed method that is very effective and robust in extracting bridge modal properties, especially under ongoing traffic flows and different road surfaces. Finally, vehicle parameters, such as the trailers’ mass and stiffness, spacing, and traveling speed, were studied to design a proper test vehicle for field applications.

During the life cycle of a bridge, dynamic impacts due to random traffic loads and deteriorated road surface conditions can induce serious fatigue issues for bridge components. It is necessary, and more realistic than the deterministic approach, to use reliability methods and treat the input parameters as random variables for the vehicle-bridge dynamic system. This paper presents a framework of fatigue reliability assessment for existing bridges in lifetime serviceability considering the random effects of vehicle speed and road-roughness condition. Since each truck passage might generate multiple stress ranges, revised equivalent stress-range is introduced to include fatigue damage accumulations for one truck passage. Therefore, the two variables, i.e., the stress-range numbers and equivalent stress ranges per truck passage, are coalesced in the newly defined variable based on equivalent fatigue damage. The revised equivalent stress-range is obtained through a fully-computerized approach toward so...