## 6 Conclusions  
The incremental hole-drilling method can be used to evaluate high residual welding stresses for welded bridge constructions. This method only applies when material behavior is linear-elastic and therefore, the effect of including the real material properties with elastic-plastic behavior on residual stresses calculated according ASTM E837-13a is studied with three-dimensional finite element modeling. The hole-drilling procedure is simulated with a calculation software. First, a linear-elastic analysis is executed to determine calibration coefficients similar to the ones specified in ASTM E837-13a for uniform in-depth residual stresses. For a uniform in-depth residual stress field, a superposition is made of equi-biaxial and deviatoric residual stress fields applied on the sides of the model. Then, the effect of plasticity on the uniform in-depth residual stresses is determined by applying an elastic-plastic material law to the same 3D model. It is concluded that the residual stresses obtained under the assumption that the material behavior is linear-elastic are an overestimation. The plasticity introduces relaxation of the material and by ignoring this, the residual stresses will be overestimated by specifying linear-elastic material behavior.  
The effect of the elastic-plastic material behavior for non-uniform in-depth residual stresses is also studied by comparing experimentally-determined radial strains with calculated strains from elastic-plastic analysis of an orthotropic steel deck. Similar behavior of the residual stresses were noticed. However, the residual stresses obtained with the elastic-plastic analysis of the finite element model are larger for tensile and smaller for compressive residual stresses.  
An accurate fatigue design including the residual welding stresses is very important since one of the most important failure modes for steel bridges with welded structural members is fatigue failure. The finite element modeling showed larger tensile residual stresses compared with the analysis according ASTM. Larger tensile residual stresses accelerate stress corrosion cracking leading to an earlier fatigue failure of the component. Therefore, it is very important to take these larger tensile residual stresses into account for the fatigue design of the welded component.  
The experimentally-determined residual stress values of the orthotropic steel deck according the ASTM standard are based on linear-elastic material behavior. The finite element modeling showed that including an elastic-plastic material model resulted in larger tensile and smaller compressive residual stresses. This behavior is more disadvantageous since it leads to premature fatigue cracking. Therefore, it is very valuable to verify the experimental hole-drilling results with finite element modeling including the material's elastic-plastic behavior.  
Conceptualization: E.V.P., W.N., and H.D.B.; Data curation: E.V.P.; Formal analysis: E.V.P.; Investigation: E.V.P., W.N., and H.D.B.; Methodology: E.V.P. and W.N.; Project administration: E.V.P., K.S., and H.D.B.; Resources: K.S. and H.D.B.; Software: E.V.P. and W.N.; Supervision: K.S. and H.D.B.; Validation: E.V.P., Z.U.-A., and W.N.; Visualization: E.V.P. and W.N.; Writing--original draft: E.V.P. and H.D.B.; Writing--review and editing: E.V.P., Z.U.-A., and H.D.B.  
This research received no external funding.  
The authors declare no conflict of interest.