OBJECT OF THE PRESENT DOCUMENT ............................................................................ 3 REFERENCE DRAWINGS & DOCUMENTS .......................................................................... 3 REFERENCES AND CODES ................................................................................................. 3 MATERIALS PROPERTIES ................................................................................................... 3 CHAPTER II: DESIGN CALCULATIONS .................................................................................... 5
2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8
DESIGN CONCEPT ............................................................................................................... 5 DESIGN LOADS..................................................................................................................... 5 LOADING COMBINATIONS ................................................................................................... 5 GEOMETRY OF CRANE LEGS ............................................................................................. 5 OVER TURNING STABILITY CALCULATIONS ..................................................................... 5 CHECK SLIDING AND SOIL CAPACITY................................................................................ 7 CHECK PUNCHING ............................................................................................................... 8 REINFORCEMENT ................................................................................................................ 8
APPENDIX A ………………………………………………………………………………………………………14
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 2 of 13
1.0
CHAPTER I: GENRALITES
1.1
OBJECT OF THE PRESENT DOCUMENT
The purpose of this document is to provide the final structural analysis and design for the footing related to the tower crane in the considered project (Northgate Retail/Office Buildings).
1.2
REFERENCE DRAWINGS & DOCUMENTS
The following drawings & documents have been used for establishing the final design of the present structure:
Foundation reaction forces Data sheet - Page 2-39 - For 52.0m height crane The above data sheets are attached. refer to appendix A.
1.3
REFERENCES AND CODES
The references of codes and standards are: - Qatar Construction Specification 2002 - BS 8110, 1997 Structural use of concrete - Code of practice For design and Construction - BS 8004, 1986 Code of Practice for Foundations - BS449, 2005 steel for the reinforcement of concrete
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 3 of 13
1.4.2 Reinforcement Steel bars of yield strength not less than 420MPa to be used for longitudinal & transversal bars. This design is for an isolated tower crane foundation. 1.4.3 Soil The allowable bearing capacity was taken 300KN/m2.
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 4 of 13
2.0 2.1
CHAPTER II: DESIGN CALCULATIONS DESIGN CONCEPT
• • • • 2.2
The footing dimensions was estimated based on over turning moment calculations with factor of safty 1.5 Checking for Sliding stability and soil capacity. Checking for Punching shear calculations for required reinforcement
DESIGN LOADS
As per manufacturer data sheet, the most critical design loads were considered for the case of crane in operation as follows: Moment (Over turning) M=4908 KN.m Horizontal force (Sliding) H=91KN gravity Load V=917 KN
2.3
LOADING COMBINATIONS
The given loads are mixed of dead loads, wind loads and live loads. However, a 1.5 ultimate factor can be considered as conservative load factor for concrete design. 2.4
GEOMETRY OF CRANE LEGS
The crane have a base dimensions with square shape of 1.98m side length. The fixing leg of 1.4m length should be embedded with 1.13m inside the footing. This means that the footing should has minimum thickness 1.40m.
2.5
OVER TURNING STABILITY CALCULATIONS
As per the figure below, the stability calculations were calculated as follows:
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 5 of 13
Figure 1: Stability against over turning
assume h=1.50m ==> over turning moment MOT = 4908+91*1.5 = 5044.5 KN.m footing weight = 25*1.5*L2 = 37.5L2 Stability moment = Mst = 917*L/2 + 37.5*L2*L/2 = 18.75 L3 + 458.5 L Use Factor of safty = F.O.S = 1.5 ==> 1.5=Mst / MOT ==> 18.75 L3 + 458.5 L - 7566.75 = 0 ==> L=6.5 m satisfy the equation.
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 6 of 13
2.6
CHECK SLIDING AND SOIL CAPACITY
- Sliding: Sliding coefficient is equal H=tan I where I=angle of internal friction ==> H=tan 30 = 0.57, Use 0.5 Sliding force = H = 91KN resisting force = (V+W)*H = (917+1584.375)*0.50 = 1250.7 >>91, OK - Soil capacity: soil stress = f = (V+W)/A ± MOT/(L*L2/6) A=footing area=L2 ==> f= 2501.375/42.25 ± 4908/(6.53/6) = 59.2 ± 107.23 Negative value is rejected ==> use another approach. refer to figure 2.
Figure 2: soil stress calculations
e=MOT/(V+W) = 4908/2501.375 = 1.96 m ==> r=1.29 m 0.5f*(3r)*L = (V+W) ==> 0.5f*3.87*6.5=2501.375 ==> f=198.88 KN/m2 < 300KN/m2, OK CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 7 of 13
2.7
CHECK PUNCHING
The fixing leg consists of several steel plates welded to the main shaft. Each plate of 350x350mm dimensions. The maximum force act for punching is considered for the case where the moments is diagonal on the footing. Fpunching = MOT/√(2*2.32) +V/4 = 4908/3.25 + 917/4 = 1510.2+229.25=1739.45 KN fs= punching stress directly at plate edge = 1.5*1739450/(4*350*d) where d=footing depth = 1500-65=1435mm ==> fs=1.3MPa << 0.8√fcu=5MPa (BS8110-1:1997, clause 3.7.7.2) it is obvious that the punching effect is very negligible.
2.8
REINFORCEMENT
For hign accuracy, the bending moment calculations were performed through finit element analysis. Autodesk ROBOT structural analysis software was used for that purpose. Note that only the large footing was considered (most critical) and the reinforcement was applied to the small one. The acting forces on the crane legs were calculated and applied to the model as follows: Compression side = M/2.3 + V/4 = 4908/2*2.3 + 917/4 = 1067+229.25=1296.25 KN Tension side = M/2.3 - V/4 = 4908/2*2.3 - 917/4 = 1067-229.25 =837.75 KN The fixing leg The following figures represent the footing geometry with acting loads, soil stress (As a verification on the manual calculations) and the service bending moments maps.
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 8 of 13
Figure 3: acting forces on footing
Figure 4: Soil reaction
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 9 of 13
Figure 5: Moment on footing
The ultimate bending moment = 347*1.5=520.5 KN.m/m ==> T25@200mm is sufficient as per following data sheet extracted from ROBOT expert software.
CLIENT:
CONSULTANT:
EQUINOX – NORTHGATE SUB CONTRACTOR:
ASSOCIATED CONSULTING ENGINEERS SUBCONSULTANT TO UNITED:
UNITED EQUIPMENTS GROUP
MZ & PARTNERS
Project: Northgate Retail/Office Building DESIGN CALCULATIONS – TOWER CRANE FOOTING
MAIN CONTRACTOR: HABTOOR LEIGHTON GROUP MZ Project No: 10109 Rev. 0 Sheet: 10 of 13
