Lecture 4_CIE 551- Part 1 (1).pdf
- 1. Structural Engineering Structural Steel Design- CIE 551 Mulungushi University Structural Steel Design- CIE 551 1 Mr. Kalolo Mukanga J.R ( B. Eng, Msc. Eng, MEIZ )
- 2. 4. Design of Plate Girders Structural Steel Design- CIE 551 2 The plate girders are I-beams made up from separate structural steel plates (rather than rolled as a single cross-section), which are welded or bolted or riveted together to form the vertical web and horizontal flanges of the beam, which are used to carry heavier load over larger span. 4.1 Basic definition & design Considerations
- 3. Structural Steel Design- CIE 551 3 Arcades Flyover Bridge- Lusaka Zambia Steel Plate Girders
- 4. Structural Steel Design- CIE 551 4 4.1.1 Need for Plate Girders As load to be carried on I beam increases and span is also large, more moment of inertia is required to resist the bending Hence more depth required. Advantages • Carry heavier load over larger span • No restriction on dimensioning of girder: - Depth , thickness of plates can be increased/decreased based on requirement. - No particular section size to be adopted.
- 5. • Freedom to chosen section for flange - Solid plate is always used as web but flanges can be taken as solid plates or different standard sections as per requirement. • Flexibility in adjusting cross section along length - Cross section can be uniform or non uniform along the length of the girder as per area of steel required at different cross sections - This is achieved by keeping depth of web same and varying the cross sections of flanges
- 6. • Freedom to provide variable depth (tapered, cranked, haunched) • Provision of holes in web girder to accommodate various services
- 7. • Economic design : - In the zone of low moment : Less flange thickness - In the zone of high shear: Thicker Web Plate • Use of Hybrid girders: - Higher grade steel in zones of high moment and shear - Standard grade steel in zones of lower values
- 8. Structural Steel Design- CIE 551 8 4.1.2 Types of Plate Girders
- 9. ⚫Railway bridges (span 15- 40 m) ⚫Highway bridges (span 24-46 m) ⚫Continuous Bridge Girders of Spans in excess of 120 m ⚫In Buildings to support heavy concentrated loads (large halls with no columns in lower storey) 4.1.3 Applications of Plate Girders
- 10. Rolled Beam Section Plate Girder ⚫Beams are rolled to standard sizes ⚫Web stiffeners not often used ⚫Standard proportion of beam ⚫Assembled by welding of plates ⚫Web stiffeners used ⚫Freedom in proportioning of girder 4.1.4 Difference between Beams and Plate Girders
- 11. 4.1.5 Components of a Plate Girders
- 12. Structural Steel Design- CIE 551 12 End of Lecture 4- Part 1