220Kv GANTRY FOUNDATIONS CALCULATIONS & BASIC DESIGN 21-20-21-E-Rev A
1.0 PURPOSE
The purpose of this document is to provide the calculations for 220kV Gantry Foundations of Vizcarra Substation as a part of the civil supply for Antamina Project.
2.0 STANDARDS & REFERENCES
Codes, specifications and standards will be the last edition, unless indicated otherwise. All structures design will be according to the following documents: Norma Técnica de Edificación E.050 – SUELOS Y CIMENTACIONES. Norma Técnica de Edificación E.030 – DISEÑO SISMORRESISTENTE Código Nacional de Electricidad. Reglamento Nacional de Construcciones (RNC) Concrete Structures Norma de Concreto Armado E-60 (ININVI) ACI Standard 318 - “Building Code Requirements for Reinforced Concrete” In addition, it will be used Uniform Building Code (UBC). Additional references: American Civil Engineers Handbook by Thaddeus Merriman. Handbook of CONCRETE ENGINEERING by Mark Fintel. Documents References: 21-14-10-S Rev. A Geotechnical Study. 21-30-10-E Basic Project Criteria. Drawing References:
220 KV VIZCARRA SUBSTATION GANTRY FOUNDATIONS CALCULATION & BASIC DESIGN 21-20-21-E Rev. A 21-24-30-E Rev. A VIZCARRA SUBSTATION – GANTRY STRUCTURES – LOAD DIAGRAM. 21-21-30-B Rev. C VIZCARRA SUBSTATION – GRADING – PLAN Sheets 1 and 2. 21-21-31-B Rev. C VIZCARRA SUBSTATION – GRADING – SECTIONS Sheets 1 and 2. 21-34-40-E Rev. B VIZCARRA SUBSTATION – GENERAL PLAN VIEW.
3.0 PROJECT DATA
3.01 WIND: Maximum Wind Velocity = 130.00km/h 3.02 GANTRY WEIGHTS: Beam Weight=3 ton Column Weight=3 ton 3.03 SOILS PROPERTIES: qs=30.00 ton/m2 Admissible Soil Capacity φ= 34.00 grades Angle of internal friction of soil hciment=1.20 m Recommended foundation depth 3.04 STABILITY CONDITIONS: The weight soil is used as stability weight, to overturning and sliding. FS volteo= 2.00 Safety factor against overturning FS deslizamiento= 1.50 Safety factor against sliding 3.05 DIMENSIONS: hpedestal1=0.15 m Gravel height from the ground hpedestal2=0.20 m Pedestal height from the gravel bx col=1.50 m X dimension of column bz col=2.50 m Z dimension of column
220 KV VIZCARRA SUBSTATION GANTRY FOUNDATIONS CALCULATION & BASIC DESIGN 21-20-21-E Rev. A 3.06 SEISMIC CONDITIONS: Zone=3 (According to Reglamento Nacional de Construcciones). Tps=0.4 Predominant period hn=15 m Height of structure 3.07 LOADS: The following were the loads considered: Wind load in X direction Wind load in Z direction Cables weight #1 (positive in Z direction). Cables weight #2 (negative in Z direction). Earthquake in X direction. Earthquake in Z direction.
4.0 CALCULATION HYPOTHESIS
4.01 MAXIMUM WIND WIND LOADS: Dimensions of tower: Bini= Bfin= Htower= Ax=
2.4 m 1.2 12 21.60m2
Initial Dimension in X Direction of metallic column Final Dimension in X Direction of metallic column. Height of tower Area X
Bini= Bfin= Htower= Az=
1.2 0.6 12 10.80m2
Initial Dimension in Z Direction of metallic column Final Dimension in Z Direction of metallic column Height of tower Area Z
According to American Civil Engineers Handbook P= F wind X=
220 KV VIZCARRA SUBSTATION GANTRY FOUNDATIONS CALCULATION & BASIC DESIGN 21-20-21-E Rev. A V nudo=
0.62 ton
Horizontal seismic force at nodes Sis .Vert .Col = 0.3 × Wcolumna
Sis. Vert. Col=
0.90 ton
Vertical seismic force at columns Sis .Vert .Vig = 0.3 × Wviga
Sis. Vert. Vig=
0.90 ton
Vertical seismic force at beams
4.03 CABLE WEIGHTS The cable weights are as shown in project drawings. 4.04 LOAD COMBINATIONS: The following were the combinations considered (see Annex #1). Cables Weight #1 (#2). Cables Weight #1 (#2) + Wind load in Z direction (+ or -) Cables Weight #1 (#2) + Wind load in X direction (+ or -) Cables Weight #1 (#2) + Earthquake load in Z direction (+ or -) Cables Weight #1 (#2) + Earthquake load in X direction (+ or -) Cables Weigh #1 + Cables Weight #2. The following were the combination design loads: Cables weight #2. Cables weight #2 + Wind load in Z direction (-). Cables weight #2 + Wind load in X direction (+). 4.05 FOOTING DESIGN The procedures to the footing design as shown in Annex #2, and include the following: CHECK THE STABILITY CONDITIONS:
220 KV VIZCARRA SUBSTATION GANTRY FOUNDATIONS CALCULATION & BASIC DESIGN 21-20-21-E Rev. A To overturning (the weight soil is considered as stability force). To sliding (the weight soil is considered as stability force). CHECK THE SOIL CONDITIONS: Soil Bearing pressure at base footings by uni -axial loading Soil Bearing pressure at base footings by biaxial loading STRESS CHECK: Flexion Design Beam action (at d from support face) Flexion Design. Shear design in One - Way action In X direction In Z direction: Shear design in Two - Way action (at d/2 from support face) FORCE TRANSFER AT INTERFACE OF COLUMN AND FOOTING 4.06 PEDESTAL DESIGN The procedures to the pedestal design as shown in Annex #2, and include the following: CHECK BY FLEXION ACTION. CHECK BY TRACTION ACTION.
5.0 CONCLUSION
According to analysis is recommended deepen the bottom level of footing to perform with Stability conditions. FINAL DIMENSIONS: FOOTING: Lx = 2.95 meters.
