Logo OZGUR
ENGINEERING Ltd.

CRANE MAT CALCULATOR

Project:
Subject:
Designer:
Date:

CRANE MAT CALCULATOR

This engineering calculator is provided by Ozgur Engineering Ltd "as-is" for informational purposes only. While efforts have been made to ensure accuracy, Ozgur Engineering Ltd makes no guarantees regarding errors, suitability, or compliance with engineering standards. The company is not liable for any damages resulting from its use. Users are responsible for verifying results and ensuring compliance with applicable standards and laws. By using this calculator, you agree to these terms.

Notes:
  1. Reference 1: TWf2022.02_Assessment and management of outrigger loading
  2. Reference 2: Effective Bearing Length of Crane Mats, David Duerr PE
  3. Pressures are assumed to be rectangular and uniform under effective lengths and effective widths, use of compressible layer under mats, such as sand or EPS, would allow for distribution of pressure more evenly (see Fig.3 and GN22 from Ref.1)
  4. For single mat enter large numbers for B2, L2 and t2. Check top mat only in calculations.
  5. Calculations are based on solid mat with crushing check omitted, top mat bearing check can be performed.
  6. Ground bearing pressure should be checked separately. Q1 for single layer mat and Q2 for double layer mat.
  7. k1 and k2 values depend on the relative stiffnesses of the mat and the ground underneath. Ground pressure distribution becomes more uniform as the ratio of mat stiffness to ground stiffness increases. Values of k1 and k2 should be selected so that the deflection and stress checks pass.
  8. Timber bog-mats on ground may be assumed to be one-way systems, stiff in the long direction only (max k1=3.7, max k2=1, see ref:2)
  9. HDPE mats are less stiff, therefore k1 and k2 values should be selected accordingly.
  10. y,max=MIN(25, 0.0075*Lc, 10*Be/1000), allowable deflection (mm), TWf guide TWf2022.02
  11. Typical Modulus of Elasticity:
    HDPE: 800-1,500MPa
    Timber: 8,800-18,500MPa
    Aluminum: 70,000MPa
    Steel: 210,000MPa
  12. This calculator uses an approximation method. For a more accurate analysis, users should integrate ground stiffness (modulus of subgrade reaction, K) into the formulas, i.e., "beam on elastic foundation".

Ref. 1: TWf2022.02, Assessment and management of outrigger loading GN22: “Stiffness capacity should ensure that the maximum calculated relative deflection within the mat (i.e. the vertical distance between the outer edge/corner and the middle of the mat) does not exceed acceptable limits. Several definitions of acceptable limits exist, including:
• 0.75 % of the cantilever length [13.], e.g.an acceptable deflection limit of 2.6 mm for a 300 mm wide outrigger on a 1 m wide outrigger mat.
• 10 mm per metre width of mat, e.g. an acceptable deflection limit of 10 mm for a 300 mm wide outrigger on a 1 m wide outrigger mat.
NOTE: It is recommended that under no circumstances should the calculated deflection in the outrigger mat exceed 25 mm, noting that this does not include additional net settlement which may occur in the underlying ground. Where this limit is not being achieved, designers should consider increasing the elastic section modulus of the mat under consideration (typically by increasing the thickness).”

INPUT

PARAMETER UNIT VALUE
MAT PROPERTIES
k1, uniform load spread in mat in long direction H/V
k2, uniform load spread in mat in transverse direction H/V
E, modulus of elasticity of mat MPa
Fb, allowable bending stress of mat MPa
Fv, allowable shear stress of mat MPa
Fp, allowable bearing stress of mat MPa
LOAD
P, load, track / outrigger t
N
B0, width of load mm
L0, length of load mm
TOP MAT
B1, width of mat mm
L1, length of mat mm
t1, thickness of mat mm
BOTTOM MAT
B2, width of mat mm
L2, length of mat mm
t2, thickness of mat mm