T Girder design (steel)

Download the design spread sheet here

This design tool is only used for initial scantling sizings of the deck girders. The reason is, much more sophisticated detailed FE analysis and beam code check is carried out using commercial Finite element softwares in the later stages of design for approval. However this tool can be effectively used in basic design.

All the information presented are taken from open source and the sheet is developed from my personnel computer for general use.

Example:

Design the beam carrying a deck load of 0.46 tons/m² as shown in the picture below. Thickness of the deck plate is 6 mm. Use high tensile steel grade AH36 with yield strength Fy = 355 MPa

Solution:

Step:1 Loads

Idealization of beam:

Finding the point load from cross beam

Assume the point load carries uniformly distributed load of 20.34 KN/m (4.52 KN/m² x 4.5m) very conservative btw

Step: 2 Analysis to find maximum bending moment and shear force

Use Continuous beam analyzer (CBANS) tool to find the shear force and bending moment diagram

Maximum shear force F_SFmax= 101.636 KN

Maximum bending moment M_max= 325.74 KN-m

Step: 3 Beam design

Use excel tool to size the beam, below is the excel calculation sample

INPUT DATA

Width of effective flange: lT = 2500.00 mm

Thk. of effective flange: tT = 6.00 mm

Height of web plate: lW = 400.00 mm

Thk. of web plate: tW = 10.00 mm

Dist. of hole center: hH = 0.00 mm

Depth of hole: lH = 0.00 mm

Width of face plate: lB = 180.00 mm

Thk. of face plate: tB = 16.00 mm

Maximum Bending moment: Mmax = 325740000.00 N-mm

Maximum Shear Force: FSFmax = 101636.00 N

Yield strength of steel: = 355.00 N/mm2

Note: The sizing of beam is preliminary, detailed FE analysis is carried out to verify strength, buckling and fatigue of the beam depends on the application.