Moving Axle Load From Multi-Span Continuous Bridge: Laboratory Study

2006 ◽  
Vol 128 (4) ◽  
pp. 521-526 ◽  
Author(s):  
Tommy H.T. Chan ◽  
Demeke B. Ashebo
Keyword(s):  
Laboratory Study ◽  
Bending Moment ◽  
Identification Accuracy ◽  
Bottom Surface ◽  
Moving Loads ◽  
Moving Vehicle ◽  
Moving Force ◽  
Computation Efficiency ◽  
Axle Loads ◽  
Good Agreement

Laboratory study on the identification of moving vehicle axle loads on a multi-span continuous bridge from the measured bending moment responses is presented. A bridge-vehicle system model was fabricated in the laboratory. The bridge was modeled as a three span continuous beam and the car was modeled as a vehicle model with two-axle loads. A number of strain gauges were adhered to the bottom surface of the beam to measure the bending moment responses. Using measured bending moment responses as an input, the corresponding inverse problem was solved to identify moving loads. The moving forces were identified when considering bending moment responses from all spans of the beam. In order to avoid the lower identification accuracy around the inner supports of continuous bridge and to improve the computation efficiency, the moving force identification from the target (one selected) span of the continuous bridge was studied. The rebuilt responses were reconstructed from the identified loads as a forward problem. To study the accuracy of the method the relative percentage errors were calculated with respect to the measured and the rebuilt bending moment responses. The rebuilt bending moment responses obtained from the identified forces are in good agreement with the measured bending moment responses. This indirectly shows that the method is capable of identifying moving loads on continuous supported bridges.

Identification Method for Moving Loads over Continuous Beam Based on Bending Moment Influence Lines

2014 ◽  
Vol 638-640 ◽  
pp. 1079-1084 ◽  
Author(s):  
Chang Zhao Qian ◽  
Chang Ping Chen ◽  
Yong Gang Xiao
Keyword(s):  
Bending Moment ◽  
High Accuracy ◽  
Inertia Force ◽  
Continuous Beam ◽  
Moving Loads ◽  
Moving Force ◽  
Identification Method ◽  
Modal Superposition ◽  
Axle Loads

Vehicle axle loads are modeled as moving loads and bridge is considered as a continuous beam. Based on the modal superposition theory, the model accelerations can be obtained from the accelerations of the bridge at several sections. Then based on the d’Alembertian theory, the inertia force of the bridge can be expressed approximately. Using the bending moment influence lines, the equations about flexural moment and moving force is obtained. Using the formulas, the moving force can be obtained at any time. Examples show that the method has high accuracy in identifying varying time moving force as well as constant moving force. This method has highly efficiency and appropriate to applying in engineering.

Numerical Simulation by CGM for Moving Force Identification

2012 ◽  
Vol 238 ◽  
pp. 826-829
Author(s):  
Zhen Chen ◽  
Jun Ling Han
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Bending Moment ◽  
Identification Accuracy ◽  
Time Varying ◽  
Acceptable Solution ◽  
Moving Force ◽  
Ill Posed ◽  
Simulation Results ◽  
The Time Domain

The conjugate gradient method (CGM) is compared with the time domain method (TDM) in the paper. The numerical simulation results show that the CGM have higher identification accuracy and robust noise immunity as well as producing an acceptable solution to ill-posed problems to some extent when they are used to identify the moving force. When the bending moment responses are used to identify the time-varying loads, the identification accuracy is more obviously improved than the TDM, which is more suitable for the time-varying loads identification.

An Improved Algorithm for Moving Force Identification

2013 ◽  
Vol 438-439 ◽  
pp. 935-938
Author(s):  
Zhen Chen ◽  
Jun Ling Han ◽  
Jun Jie Li
Keyword(s):  
Time Domain ◽  
Noise Immunity ◽  
Bending Moment ◽  
Identification Accuracy ◽  
Time Varying ◽  
Force Identification ◽  
Moving Force ◽  
Ill Posed ◽  
Preconditioned Matrix ◽  
The Time Domain

The pretreatment conjugate gradient method (PCGM) is proposed to improve the ill-posed problem of moving force identification. Compared with the time domain method (TDM), the identification accuracy of the time-varying bending moment responses is more obviously improved. Meanwhile, the pretreatment matrix is very important to the PCGM because it affects the identification accuracy and robust noise immunity as well as ill-posed problems identification to some extent, choosing proper preconditioned matrix can effectively improve both of identification accuracy and efficiency of the PCGM.

Dynamic Responses of a Simply Supported Bridge to Moving Vehicle Loads

2011 ◽  
Vol 117-119 ◽  
pp. 231-235 ◽  
Author(s):  
Jeng Hsiang Lin
Keyword(s):  
Time Domain ◽  
Analytical Approach ◽  
Dynamic Responses ◽  
Integral Approach ◽  
Convolution Integral ◽  
Moving Vehicle ◽  
Simply Supported ◽  
Vehicle Loads ◽  
Axle Loads ◽  
Good Agreement

The estimation of dynamic responses of a bridge under vehicle loads moving along the bridge is frequently a problem of great interest for bridge engineers. Presented herein is an analytical approach to estimate the dynamic responses of a simply supported Euler-Bernoulli bridge under a set of vehicle axle loads moving along the bridge at constant speed. The approach involves convolution of the vehicle axle loads with modal responses of the bridge. The convolution integral is solved in time domain by a numerical integral approach. The solution was verified and good agreement was found.

Bidirectional Moving Force Identification on an Orthotropic Rectangular Plate

2011 ◽  
Vol 378-379 ◽  
pp. 171-175
Author(s):  
Wei Zhang ◽  
Ling Yu
Keyword(s):  
Dynamic Programming ◽  
Orthotropic Plate ◽  
Bridge Deck ◽  
Identification Problem ◽  
Least Square ◽  
Identification Accuracy ◽  
Dynamic Programming Method ◽  
Moving Vehicle ◽  
Moving Force ◽  
Bridge Responses

Based on the modal superposition and dynamic programming theory, a method is proposed to identify bidirectional moving forces from orthotropic plate bridge responses in time domain. The bridge deck is modeled as an orthotropic plate and the moving vehicle loads are modeled as two groups of axle loads moving cross the bridge deck in two opposite directions. The equation of motion is formulated in state space and the resulting damped least-square identification problem is solved using the dynamic programming method with regularization on the solution. Some numerical simulations show that the proposed method is effective, accurate and suitable for the bidirectional moving vehicle load identification. Some parameter effects of measurement noise and of eccentricity of moving loads on the identification accuracy are discussed as well.

Experimental Investigation on the Effect of Arm Length on Accuracy of Torque Wrench

2016 ◽  
Vol 853 ◽  
pp. 216-220 ◽  
Author(s):  
You Gang Peng ◽  
Yong Wang
Keyword(s):  
Experimental Investigation ◽  
Structural Design ◽  
Bending Moment ◽  
Theoretical Solution ◽  
Calibration Laboratory ◽  
Moment Measurement ◽  
Torque Wrench ◽  
Actual Use ◽  
Good Agreement

Experiments were carried out to investigate the effect of arm length on the accuracy of two typical conventional torque wrenches, namely, setting type torque wrench (STW) and indicating type torque wrench (ITW). The experiment results demonstrate that the measurement values of STW rises rapidly with decreasing arm length while measured torque of ITW shows irrelevant to arm length. Theoretical solution with respect to STW shows quite good agreement with experiment results. Irrelevance of arm length regard to ITW may be attributable to compensation of bending moment measurement due to proper arrangement of circuit and structural design. In order to conduct a proper assessment at a calibration laboratory or ensure its reliability with reference to actual use conditions, a torque wrench should be used by a customer at the loading point as recommended.

On the Effect of Hull Girder Flexibility on the Vertical Wave Bending Moment for Ultra Large Container Vessels

2012 ◽  
Author(s):  
Ingrid Marie Vincent Andersen ◽  
Jørgen Juncher Jensen
Keyword(s):  
Bending Moment ◽  
Main Concern ◽  
Hull Girder ◽  
Numerical Predictions ◽  
Strip Theory ◽  
Reliability Method ◽  
Non Linear ◽  
Large Container ◽  
The Waves ◽  
Good Agreement

Currently, a number of very large container ships are being built and more are on order, and some concerns have been expressed about the importance of the reduced hull girder stiffness to the wave-induced loads. The main concern is related to the fatigue life, but also a possible increase in the global hull girder loads as consequence of the increased hull flexibility must be considered. This is especially so as the rules of the classification societies do not explicitly account for the effect of hull flexibility on the global loads. In the present paper an analysis has been carried out for the 9,400 TEU container ship used as case-ship in the EU project TULCS (Tools for Ultra Large Container Ships). A non-linear time-domain strip theory is used for the hydrodynamic analysis of the vertical bending moment amidships in sagging and hogging conditions for a flexible and a rigid modelling of the ship. The theory takes into account non-linear radiation forces (memory effects) through the use of a set of higher order differential equations. The non-linear hydrostatic restoring forces and non-linear Froude-Krylov forces are determined accurately at the instantaneous position of the ship in the waves. Slamming forces are determined by a standard momentum formulation. The hull flexibility is modelled as a non-prismatic Timoshenko beam. Generally, good agreement with experimental results and more accurate numerical predictions has previously been obtained in a number of studies. The statistical analysis is done using the First Order Reliability Method (FORM) supplemented with Monte Carlo simulations. Furthermore, strip-theory calculations are compared to model tests in regular waves of different wave lengths using a segmented, flexible model of the case-ship and good agreement is obtained for the longest of the waves. For the shorter waves the agreement is less good. The discrepancy in the amplitudes of the bending moment can most probably be explained by an underestimation on the effect of momentum slamming in the strip-theory applied.

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