Vibration & Dynamics

Dynamic Analysis of steel-girder bridges using continuous beam theory

Fig 1. Multi-span continuous bridge under a group of moving forces

Fig 2. Flow chart of Wilson θ integration method

Fig 3. MATLAB software for beam analysis

Runge-Kutta Method (Transient Vibration)

Finite Difference Numerical Computation (Transient Vibration)

Software for WVU Weigh-in-Motion System

Presented By: Yan Luo

Sept. 7, 2006

1. Introduction

WVU Weigh-in-Motion (WIM) System is a system developed in MAE, West Virginia University, in order to estimate static tire loads of a vehicle by measuring the dynam

ic tire forces of the moving vehicle.

Fig.1 Splash Window of the WVU WIM System software

The WIM System is expected to collect and process data received from sensors embedded at the surface of the highway. Data collected by the WIM System can be used in planning, design, operations, and maintenance activities related to both highway pavements and bridges. WIM Systems are also developed for the purpose of collecting truck data in a more efficient manner than by using conventional weighing methods (static weighing).

The purpose of this software is to process and analyze the data obtained by the WIM hardware system. With friendly interfaces, all functions are easy to use.

The software can do statistical analysis based on the original data of one day, one month or even one year. You can easily get the statistical plots, such as Distribution of No. of Axles, Speed Distribution, Axle-Weight Distribution, Gross-Weight Distribution, and etc.

The change of battery voltage and control-box temperature for one day period can be easily observed. Furthermore, classification can be done based on the axle distance.

The console can be accessed by activating HyperTerminal to control the WIM hardware if the computer is connected with the hardware. For some special purpose, the raw data can be loaded and displayed.

A report of the WIM data can be easily created, which can be edited and printed out, and even exported to other formats (Excel, CSV and HTML) for other purposes or further analysis.

Meanwhile, calibration can be easily done through the software.

Fig.2 Function Overview

2. Main Functions

There are four main functions relative to the corresponding buttons in the Main Window (Fig.3):

• Part I: Statistics (load data and do statistical analysis and classification)
• Part II: Communicate (invoke HyperTerminal to communicate with the WIM hardware for some special purpose, such as system monitoring & testing, raw data collection, system time settings and so on. The computer needs to be connected with the WIM data collection box by a serial cable)

• Part III: Data Plot (plot & analysis the raw data)
• Part IV: Calibration (do WIM system calibration)

Fig.3 Main Window

2.1 Statistical Analysis

In the Statistics Window (Fig. 4), WIM data can be loaded and read, and then series of statistics plots can be created, including Battery Voltage, Temperature, Axle Distribution, Speed Distribution, Axle Weight Distribution and Gross Weight Distribution. And based on axle distance of vehicles, basic classification can be achieved.

Fig.4 Statistical Analysis Window

The following figures are presented as an example of analysis:

Fig.5 Battery Voltage Curve & Temperature Curve

Fig.6 Distribution of No. of Axles & Distribution of Speed

Fig.7 Distribution of No. of Axles & Distribution of Speed

Fig.8 Classification for 5-axle Vehicles

Fig.9 Report for WIM Data Statistical Analysis

2.2 Communication with WIM Hardware

This function can invoke HyperTerminal to communicate with the WIM hardware for some special purpose, such as system monitoring & testing, raw data collection, system time settings and so on. (The computer needs to be connected with the WIM data collection box by a serial cable.)

2.3 Raw Data Plot

The software can read and plot the raw data in the “Data Plot” section. The data plot panel and an example of raw data is shown in Fig.10. In the figure, the original signal from loops and sensors are plotted. For the case, the raw data came from a five-axle truck.

Fig.10 Data Plot Panel & Raw Data of a Five-axle Truck

2.4 Calibration

Calibration can be easily done through the “Calibration” section. The only thing you need to do is to input the wheel weights of the calibration vehicle. After loading the calibration WIM data, the software will calculate the WIM factors automatically, which shorten a lot of time for calibration calculation. Also, the calibration data sheet can be exported to Excel file, which allows you to do further analysis or drawings in Excel.

Fig.11 Calibration Data Sheet

Fig.12 Calibration Data Sheet in Excel

Fig.13 Drawings of Calibration Data in Excel

2D Truss Analysis GUI

A GUI program which can help you to easily solve the 2D truss problem step by step.

Download Link: http://www.mathworks.com/matlabcentral/fileexchange/7930-2d-truss-analysisgui

Wireless Bridge Load Testing & Rating System

Dissertation Abstract

Wireless Sensing System for Load Testing and Rating of Highway Bridges

Yan Luo

Structural capacity evaluation of bridges is an increasingly important topic in the effort to deal with the deteriorating infrastructure. Most bridges are evaluated through subjective visual inspection and conservative theoretical rating. Diagnostic load test has been recognized as an effective method to accurately assess the carrying capacity of bridges. Traditional wired sensors and data acquisition (DAQ) systems suffer drawbacks of being labor intensive, high cost, and time consumption in installation and maintenance. For those reasons, very few load tests have been conducted on bridges.

This study is aimed at developing a low-cost wireless bridge load testing & rating system that can be rapidly deployed on bridges for structural evaluation and load rating. Commercially available wireless hardware is integrated with traditional analogue sensors and the appropriate rating software is developed. The wireless DAQ system can work with traditional strain gages, accelerometers, etc. A wireless truck position indicator (WVPI) is developed and used for measuring the truck position during load testing. The software is capable of calculating the theoretical rating factors based on AASHTO Load Resistance Factor Rating (LRFR) codes, and automatically produce the adjustment factor through load testing data. A simplified finite element model was used to calculate deflection & moment distribution factors in order to reduce the amount of instrumentation used in field tests. The system was used to evaluate the structural capacity of Evansville Bridge in Preston County, WV. The results show that the wireless bridge load testing & rating system can effectively be implemented to evaluate the real capacity of bridges with remarkable advantages: low-cost, fast deployment and smaller crew.