Parameter Estimation of Structures from Static Strain Measurements. II: Error Sensitivity Analysis

Abstract

A method for the parameter estimation of structures was d~veloped in a companion pape~. It used subsets of static applied forces and strain measurements and successfully Identified structural element stlffnesses. In the presence of noisy measurements, the selection of these s~b~ts drastically affect the accu~acy of the parameter estimates. In addition, there are a large number of combmatlons of~pplied force and stram measurements to be considered. Therefore, a heuristic method is presented for choosmg a small subset of forces and strain measurements so as to have the least sensitivity to measurement noise. Once chosen, using a Monte Carlo analysis the subset of measurements is analyzed to determine an input-out~ut err~r relationship. This h.euri~tic method can be used to design near-optimal experiments for the nondestructIve testing and parameter estimatIOn of structures. A truss and a frame example are presented and a small and noise-tolerant subset of forces and strains is successfully selected for possible nondestructive testing.

Fatigue Performances of Steel Box Girder in Orthotropic Steel Bridge Deck with Corrosive Environment

“…Because of the complex load distribution, multivariable structural form, stress concentration in welding site and inevitable welding flaws, fatigue failure tends to happen in bridge decks. Steel box girder generally is composed of roof, floor, web stiffeners, horizontal clapboard, web plate and stiffener [7][8]. The use of steel box girder bridges as the main load-bearing components can be traced back to Germany after the second world war, because of the shortage of steel, German needs to build and rebuild a large number of bridges to restore the post-war economy.…”

Sensor Placement for Structural Damage Detection considering Measurement Uncertainties

“…Moreover, the maximum number of measurement locations is limited due to technological and economical reasons. The measurement locations and the modes that are included in the analysis significantly influence the accuracy of the damage identification results (Sanayei and Saletnik 1996;Gunes et al 1999;Xu and Wu 2009). Therefore, a proper measurement subset needs to be chosen carefully before field testing and damage identification analysis to ensure successful and efficient damage identification.…”

“…Sanayei and Saletnik (1996) developed a best-in-worstout approach to select a subset of static force and strain measurements with the least sensitivity to measurement noise. The available measurement with the smallest effect on the parameter estimation is removed one by one until the output error becomes significant.…”

Measurement Selection for Vibration-Based Structural Damage Identification

“…Therefore, the number of equations in model updating is usually smaller than that of unknown parameters of the model, hence, it is an underdetermined problem and a small error may cause a large deviation in the results [5]. It has been realized that the locations of measurement and the modes that included in the analysis have a great in#uence on the accuracy of damage identi"cation results [6,7]. Therefore, to identify damage successfully, proper measurement selection including the measurement points and modes need to be chosen carefully before "eld testing and damage identi"cation analysis.…”