Eccentric connections in steel structure

bracket connection type I & II are compared by elastic method and other two methods( geometric & ultimate) are just mentioned but not explained

1. Eccentric Connections in Steel Structures Presented by- Sarvesh Sureshrao Chikte

2. CONTENT Introduction Literature Review Theoretical Background Experimental Analysis Conclusion References

3. Introduction 1) Types of connection 2) Connection Subjected to eccentric shear 3) Methods of analysis

4. TYPES OF CONNECTIONS SIMPLE CONNECTIONS ECCENTRIC CONNECTIONS Basis of classification – C.G of connection & load axis.

5. SIMPLE CONNECTIONS Fig -1a Fig -1b Applied load passes through C.G of connections

6. ECCENTRIC CONNECTIONS Applied load does not pass through C.G of connections Fig 2

7. CONNECTIONS SUBJECTED TO ECCENTRIC SHEAR Seat Connections Framed Connections Bracket Connections

8. SEAT CONNECTION Fig 3a – Unstiffened Seat Connections

9. Fig 3b – S tiffened Seat Connections SEAT CONNECTION

10. FRAMED CONNECTIONS Fig - 4

11. BRACKET CONNECTIONS Bolted bracket – type I connections Bolted bracket – type II connections Welded bracket – type I connections Welded bracket – type II connections

12. Methods of analysis Elastic method Rigid plastic method Ultimate method Geometric method

13. Literature Review Dr D. M. F. Orr , “The strength of Eccentrically loaded Shear connections” , Vol 2, Journal of Constructional Steel Research , 1982 John R. Veillette1 and John T. DeWolf, “ECCENTRICALLY LOADED HIGHSTRENGTH BOLTED CONNECTIONS” , 111(5), Journal on Structural Engineering, 1985   P. S. Nowak and T. W. Hartmann, “ECCENTRIC CONNECTION DESIGN: GEOMETRIC APPROACH” , 119(2) , 1993   Harish N. Sayankar, Prof. S. D. Khamankar, “Experimental and FE Analysis of Eccentric Loaded Welded Joint Structure” , Vol 4, Issue 8 , Int. journal of Engineering research and application , 2014

14. Theoretical Background BRACKET CONNECTIONS BOLTED BRACKET CONNECTIONS TYPE 1 Fig 5

15. FORCES ON BRACKET TYPE 1 Fig 6

16.  From the assumption made in the concentric bolted joints, ‘ the load over the joint is shared equally by all the bolts’ ,force in any bolt due to direct load is,   ( 1) We know that, And also Force = Stress * Area Therefore, F 2 = k*r  

17. Therefore, the Torque about the center of rotation of the bolt group Total resisting toq The resisting torque should be equal to torque over the connection. Hence,  

18. Force F 2 is maximum when distance r is maximum. Let the distance of the extreme bolt be r n . then , (2) The two forces F 1 and F 2 act at some angle on various bolts in the connection. Let be the angle between these forces on the critical bolt. Then the resultant force F on the critical bolt will be (3) For the connection to be safe, this force must be less than the strength of the bolt.  

19. M = torque in Nmm (caused by the eccentric load) = load * eccentricity e = the perpendicular distance measured from the center of rotation of the bolt group to the line of action of load, called eccentricity P = the eccentric load acting over the joint in N r 1 , r 2…. r n = the distances of the bolts from the center of rotation of the bolt group. n = number of bolts in the bolt group F 1 = force in a bolt due to direct shear P F 2 = force in bolt due to torque M k = elastic constant From equation of resultant F it is evident that F depends upon F 1, F 2 and . For the resultant force F to be maximum with F 1 being same for all the bolts and F 2 being maximum for the bolt farthest from the center of gravity of the joint, the angle between the forces has to be minimum.  

20. BOLTED BRACKET CONNECTIONS TYPE 2 Fig 7

21. From the assumption made in the concentric bolted joints, ‘the load is shared equally by all bolts’, Forces F 1 in any bolt due to direct load The tensile force in the bolt is proportional to the distance of the bolt from the line of rotation. Moment of resistance due to tensile force in a bolt, = Total moment of resistance due to tensile force,  

22. For equilibrium,, total compressive force C should be equal to total tensile force. Hence, total compressive force, External moment = moment resisted by the bolts in tension + moment of the compressive force.  

23. Where, M = Pe moment in Nmm , caused by the eccentric load e = the eccentricity of the load P from the bolt plane to the line of action of load in mm P = the load acting over the joint in N M’ = moment of resistance provided by bolts in tension V b = force in a bolt due to direct shear P T b = tensile force in the bolt due to bending moment (Pe ) n = number of bolts in the bolt group y 1 ,y 2…. y n = distance of the bolts in tension from the axis of rotation y = distance as shown in figure.

24. WELDED BRACKET CONNECTIONS TYPE 1

25. WELDED BRACKET CONNECTIONS TYPE 2

26. Experimental Analysis Reference paper -The Strength of Eccentrically Loaded Shear Connections (Ultimate Method)

27. Reference paper - Eccentric Connection design- geometric approach (Geometric Method)

28. Reference Paper -Experimental and Fe Analysis of Eccentric Loaded Welded Joint Structure (Elastic Method)

29. Conclusion Different method of analysis are compared If priority is less computational efforts go for elastic method If number of connections are less go for geometric approach If number of connections are more , use elastic approach Limitation of ultimate method – trial and error method Limitation of geometric method – if lengthy & tedious calculations Limitation of elastic method – assumes linear load-deformation relationship

30. References   X.C. Liu ⁎, S.H. Pu , A.L. Zhang, A.X. Xu , Z. Ni, Y. Sun, L. Ma , “Static and seismic experiment for bolted-welded joint in modularized prefabricated steel structure” ,115, Journal of Constructional Steel Research, 2015   X.C. Liu ⁎, A.X. Xu , A.L. Zhang, Z. Ni, H.X.Wang , L. Wu , “Static and seismic experiment for welded joints in modularized prefabricated steel structure” , 112, Journal of Constructional Steel Research, 2015   Dr D. M. F. Orr , “The strength of Eccentrically loaded Shear connections” , Vol 2, Journal of Constructional Steel Research , 1982   John R. Veillette1 and John T. DeWolf, “ECCENTRICALLY LOADED HIGH STRENGTH BOLTED CONNECTIONS” , 111(5), Journal on Structural Engineering, 1985   P. S. Nowak and T. W. Hartmann, “ECCENTRIC CONNECTION DESIGN: GEOMETRIC APPROACH” , 119(2) , 1993   Harish N. Sayankar, Prof. S. D. Khamankar , “Experimental and FE Analysis of Eccentric Loaded Welded Joint Structure” , Vol 4, Issue 8 , Int. journal of Engineering research and application , 2014

31. By Murty K. S. Maduguia1 and S. Mohan2, ANGLES IN ECCENTRIC TENSION J. Struct . Eng., 114(10) 1988   Akbar Pirmoz ,_, Amir Saedi Daryan , Ahad Mazaheri , Hajar Ebrahim Darbandi , Behavior of bolted angle connections subjected to combined shear force and moment , Journal of Constructional Steel Research 64 (2008)   Konstantinos E. Kalochairetis ⁎, Charis J. Gantes , Xenofon A. Lignos , Experimental and umerical investigation of eccentrically loaded laced built-up steel columns, Journal of Constructional Steel Research 101 (2014)

32. Thank You