1. Experiments and Simulations of an Innovative Performance Enhancement Technique for Steel Building Beam-Column Connections Machel Morrison Doug Schweizer Tasnim Hassan (PI)

2. Post Northridge Research AISC 341 Performance Criteria θ d =0.04 Radians Bolted Extended Endplate Bolted Flange Plate Kaiser Bolted BracketReduced Beam SectionWUF-W Figures from Hamburger et. al 2009

3. Heat Treated Beam Section (HBS) M f ∝ M RBS M f ∝ M HBS

4. Heat Treated Beam Section (HBS) Figure from : http://textbooks.elsevier.com

5. Induction Heating - Eddy currents “induced” by alternating magnetic field Advantages: Lower energy Input than traditional heating sources Easy to localize heat input Induction heating provided by Ameritherm Inc.

6. Induction Heating Challenges: - Difficult to control temperature uniformity - Prescribed slow cooling rate was not achieved

7. Experimental Program -4 Full Scale WUF-W -3 HBS and 1 Unconditioned -Sub assemblage similar to Engelhardt et al 1998- DB5

8. Experiment Results 0

9. HBS Experiment Results WUF-W HBS

10. Experiment Results WUF-W

11. Challenges -Significant yielding spread beyond HBS region and higher moments than expected

12. FE Simulations -Finite Strain, Large Displacement Formulation -Initial Geometric Imperfections (Flange thickness variation, out of straightness) - Quadratic Shell Elements ANSYS 12.1 Mechanical ADPL

13. FE Simulation- Constitutive Model -Non Linear Kinematic Hardening Model (Chaboche 1986) Chaboche Kinematic Hardening Rule Yield Surface Flow Rule

14. Validation of FE Simulation

15. WUF-W

16. FE Simulation Results

17. Expt Results- Flange Buckling HBSWUF-W

18. Validation of FE Simulation

19. FE Results- Flange Buckling

20. Shear tab w/Supplemental Weld No Shear tab/Supplement weld

21. FE Results- Flange Buckling

22. FE Results –Flange Buckling WUF-W Ricles et. al 2002

23. Summary -Heat treatment of beam flanges reduces strength of steel and initiates yielding in the heat treated regions - Future experiments are being planned with new heat treatment technique -Uniform heat pattern difficult to achieve with Induction heating, σ-ε response varied from furnace heat treatment -Heavy shear w/supplemental fillet weld to beam web influences local flange buckling

24. Acknowledgments -National Science Foundation (NSF) -Network for Earthquake Engineering Simulation (NEES) -MAST LAB @ U of Minnesota -Lejune Steel Company -Ameritherm Inc.

25. New Heat treatment Technique

26. COMPARISON WUF-W, HBS & RBS WUF-W No Shear tab/Supplemental weld HBS No Shear tab/Supplemental weld RBS No Shear tab/Supplemental weld

27. COMPARISON WUF-W, HBS & RBS WUF-W From Hassan and Syed 2009

28. Moment Response