Tower Crane - Design Details

Design Check for Crane Supporting Boom for the Crane

The Crane tower needs to be supported laterally at certain interval from the RCC Building.

The interval can be say 30m.

The manufacturer has given a lattice section to be used as a lateral supporting member.

Check the capacity of the member under compression:

A = 4 Nos X 7.44 Cm²   = 29.76 Sq.m

L = 11m

I = A.x²   = 4 ( 7.44 X (30/2 - 1.81)² )

I = 5177 Cm⁴

Therefore,   r =   I/A =   5177/29.74 = 13.1 cm

Therefore l/r _{min  =}

        

                = 950 Kg/cm²

Therefore, Capacity of the section under compressive load =  σa.A

= 950 Kg/cm²    X 29.76 cm²

Pc = say 28T

In the absence of any specific load data,

Assuming maximum force in the connecting member can be plus/minus 10T maximum, the member seems to be safe.

The actual length of the member can be checked as per the site condition and the length of the member can be extended up to 11m as required upto splice joint.

(II) End Anchorage at the building slabs:

Try 6 Nos of M16 bolts to resist the force of 10T.

Assuming permissible shearstress = 1000 Kg/Cm²

Shear Capacity of one M16 bolt

= σss x net area

= 1000X 0.75 X П / 4X (1.6) ²

= 1000X1.5

= 1500 Kg

Total Force resisted by 6 Bolts = 6 X 1.5T = 9T < 10 T

Try M20 Bolts,

Shear capacity = 1000 X 0.75 X П / 4X (2) ²

                                       = 2355 Kg

Therefore Total Force Resisted by 6 Bolts

= 6 X 2.3T = 13.8 T > 10 T

Therefore, Provide 6 Nos M25 Bolts to connect the member with the building.

As per calculations, Crane tie should be provided in 7^TH Floor, 14^TH Floor and 19^TH Floor respectively.