Diseño Del Aro De Concreto Para Tanques De Almacenamiento

Design of Concrete Ring Beam for Storage Tank

In this page I will talk about the design philosophy of ring beam for storage water tank. The granular fill foundation of the tank shall be designed per project design criteria / specification. This type of foundation is mostly common to all project site. However, sometimes we design concrete ring beam around the tank foundation. Following aresome reasons for design of concrete ring beam, though this is more costly and take longer to construct than granular fill ring:

• Sometimes clients ask to provide concrete ring beam around tank foundation.
• Prevent uplift of the tank due to wind or earthquake
• Prevent edge failure of the soil at the tank shell
• Prevent local uplift of the tank due to internal pressure.Now you will follow the following steps to start the foundation load calculation and design:

Step #1: Review of Tank detail drawing (Vendor Drawing)

You need to review tank drawings from foundation design point of view and check whether you have all the following information:

• Tank Dimension, Diameter and Height
• Type of Roof (Floating or fixed roof), weight of roof
• Detailof tank shell and weight of tank shell
• Detail of tank base plate, location of base sump, annular plate and total weight of base plate
• Detail of anchor bolt (BCD, no of bolt and dia of bolt) and anchor bolt fixing detail
• Location and detail of man-hole at bottom portion of tank
• Product density and and maximum height of product
• Maximum height of water inside thetank for the hydrotest* Internal pressure or suction
• Live load
• Wind Shear and moment on tank shell
• Seismic shear and moment on tank shell

Step #2 : Verification of foundation location, elevation and external fittings loads

You need to review Plot plan, Equipment location drawings and 3 -D Models and check whether you have all the following information:

• Verify thearea available for foundation;
• Verify Foundation location and Elevation;
• Pipe supports and Nozzle loads on tank (Dp);
• Location and size of Platforms around the tank;
• Locations of underground pipes;
• Electrical and Instrument duct banks;
• Locations and extent of adjacent foundations;
• Verify the location and extent of new/existing foundations not shownin 3D model or plot plan.

Step #3: Loads on concrete ring beam and on the confined compacted granular fill in-side the ring:

You need to place concrete ring beam in such a way that outer surface of the tank shell should be the center of ring beam. Consider the following loads on ring beam and on granular compacted fill inside the concrete ring.

Geotechnical Data:

Before starting thedesign, you need to collect the following information about soil:

• Allowable Bearing Pressure;
• Density of Soil;
• Co-efficient of earth pressure at rest (Ko).

Loads on Ring beam:

• Total weight of tank shell (vertical load), kN / m (DL);
• Total weight of roof, for fixed roof case. For floating roof, part of the roof weight will come on the ring beam, kN / m(DL);
• Total live load on roof, for fixed roof case. For floating roof, part of the live load will come on the ring beam, kN / m (LL);
• Part of annular base weight on ring beam, kN / m2 (DL);
• Part of product / test water load on ring beam, kN / m2(PL);
• Seismic shear and wind shear on ring beam, kN / m;
• Part of internal pressure / suction load on ring beam, kN / m2(IP).

Loads on compacted granular fill inside the ring beam:

• Floating roof weight on compacted granular fill, kN / m2(DL);
• Annular base weight on compacted granular fill, kN / m2 (DL);
• Live load on floated roof, kN / m2 (LL);
• Product / test water load on compacted granular fill, kN / m2(PL);
• Internal pressure / suction load on compacted granular fill, kN /...