ECPIT -RC Rectangular Pit Design

This part of user manual describes how to use ECPIT for the design of Concrete Pit. ECPlus applications are designed as wizard type which is a step by step guided input procedure. If you are new to ECPlus applications, click here for general guidance.

Prerequisites: The user is expected to have a basic understanding of foundation design concepts.
The minimum input data required to use this application is as follows:

• ❶ Soil data such as Safe Bearing Capacity and ground water table.
• ❷ Allowable stability factors
• ❸ Concrete and Reinforcement Grades
• ❹ Dimension and Material Properties
• ❺ Pit Loads

Following sections are presented with various input pages of ECPIT application with descriptions:

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Design Standard

This page allows to enter the dimensions of the rectangular pit and top slab.

Design Standard

Select the National Standard for the design. Available Standards: ☉British, ☉European and ☉American.

Unit

It displays the active unit. The unit   Change   button is displayed when ☉American Standard is selected.

British and European Standards can not be selected when Imperial unit is active.

Change

Click this button to open the unit change pop-up dialog.

☐  Reset all Input Data
This option will reset the input data for the new unit. This option is recommended if the job is new and no input data has been entered yet.

☐  Convert Dimensions and Properties
This option allows to convert all the previously entered input data except Load data to the new unit.

☐  Convert Loads
This option allows to convert previously entered load data to the new unit.

Note: Both Convert Dimensions and Properties and Convert Loads options can be used simultaneously to convert all the previously entered input values to the new unit.

Incorrect option leads to out of range errors and should be manually corrected.

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Dimensions

This page allows to enter the dimensions of the rectangular pit and top slab.

Breadth - B_p

Enter the breadth of the rectangular pit.
↔ Range: >= 500 mm (>= 20 inches)

Length - L_p

Enter the length of the rectangular pit.
↔ Range: >= 500 mm (>= 20 inches)

Thickness of the Wall - t_wall

Enter the thickness of wall of the rectangular pit.
↔ Range: 100 to 1000 mm (4 to 40 inches)

Top Cover

▽ Monolithic: Select this option to design pit and top slab as monolithic.
▽ Non Monolithic: Select this option to design pit and top slab as non monolithic.
▽ Steel Platform: Select this option, if top cover is made of steel platform.
▽ Not Present: Select this option, if top cover is not present.

Thickness of Top Slab - t_top

Enter the thickness of the top slab.
↔ Range: 100 to 1000 mm (4 to 40 inches)

Thickness of Bottom Slab - t_bot

Enter the thickness of the bottom slab.
↔ Range: 100 to 1000 mm (4 to 40 inches)

Projection of Bottom Slab beyond Wall - proj

Enter the projection of bottom slab beyond the side walls of rectangular pit.
↔ Range: 0 to 2000 mm (0 to 80 inches)

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Levels

This page allows to enter the reference levels of concrete pit.

Reference Ground Level Elevation - GL

Enter the elevation of reference ground level.
↔ Range: 0 to 500 m (0 to 1650 ft)

Top of the Wall / Top Slab Elevation - W_ele

Enter the elevation of top of the wall.
↔ Range: -500 to 500 m (-1650 to 1650 ft)

Top of Bottom Slab Level - B_SL

Enter the elevation of bottom of the wall.
↔ Range: -500 to 500 m (-1650 to 1650 ft)

Maximum Ground Water Level Elevation - GWL

Enter the elevation of maximum ground water.
↔ Range: -500 to 500 m (-1650 to 1650 ft)

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Contents

This page allows to enter the details of contents inside the concrete pit.

Content Inside Tank

▽ Sand: Select this option if content inside tank is sand.
▽ Liquid: Select this option if content inside tank is liquid.
▽ Nil: Select this option if there is no content present inside the tank.

Content inside tank: Sand

Unit Weight of Content - γ_cont

Enter the unit weight of the content inside the pit.
↔ Range: 5 to 50 kN/m³ (30 to 350 pcf)

Shear Angle of Content - Φ_c

Enter the shear angle of the content inside the pit.
↔ Range: 10 to 50 Deg

Weight of Equipment - W_L

Enter the weight of the equipment inside the pit.
↔ Range: 0 to 1000 kN (0 to 25000 kips)

Volume of Equipment - V_L

Enter the volume of the equipment inside the pit.
↔ Range: >= 0 m³ (>= 0 ft³)

Free Board - FB

Enter the free board of the content inside the pit.
↔ Range: >= 0 m (>= 0 ft)

Content inside tank: Liquid

Unit Weight of Content - γ_cont

Enter the unit weight of the content inside the pit.
↔ Range: 5 to 50 kN/m³ (30 to 350 pcf)

Weight of Equipment - W_L

Enter the weight of the equipment inside the pit.
↔ Range: 0 to 1000 kN (0 to 25000 kips)

Volume of Equipment - V_L

Enter the volume of the equipment inside the pit.
↔ Range: >= 0 m³ (>= 0 ft³)

Free Board - FB

Enter the free board of the content inside the pit.
↔ Range: >= 0 m (>= 0 ft)

Content inside tank: Nil

Weight of Equipment - W_L

Enter the weight of any equipment present inside the pit.
↔ Range: 0 to 1000 kN (0 to 25000 kips)

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Reinforcement

This page allows to enter the details of reinforcement for concrete pit and slab.

Cover

Clear Cover for Wall - C_wall

Enter the clear cover for wall.
↔ Range: 20 to 100 mm (0.5 to 6 inches)

Clear Cover for Top Slab - C_tslab

Enter the clear cover for top slab.
↔ Range: 20 to 100 mm (0.5 to 6 inches)

Clear Cover for Bottom Slab - C_bslab

Enter the clear cover for bottom slab.
↔ Range: 20 to 100 mm (0.5 to 6 inches)

Wall

☐   Single Layer
Check this option to provide single layer of reinforcement to wall of concrete pit.

☐   Short / Long Wall same Reinforcement
Check this option to provide same reinforcement for both short and long walls of concrete pit.

Short Wall / Long Wall

This popup buttons are used to enter reinforcement details for short and long walls correspondingly.

Slab

Bottom Slab / Top Slab

This popup buttons are used to enter reinforcement details for bottom and top slabs correspondingly.

Short Wall

Click this button to open the reinforcement pop-up for the short wall.

Size

Select the rebar size for horizontal and vertical layers of both short wall of concrete pit.
↔ Range: 4 to 50 mm

Spacing

Enter the spacing of reinforcement for horizontal and vertical layers of short wall of concrete pit.
↔ Range: 20 to 450 mm (1 to 18 inches)

Long Wall

Click this button to open the reinforcement pop-up for the long wall.

Size

Select the rebar size for horizontal and vertical layers of long wall of concrete pit.
↔ Range: 4 to 50 mm

Spacing

Enter the spacing of reinforcement for horizontal and vertical layers of long wall of concrete pit.
↔ Range: 20 to 450 mm (1 to 18 inches)

Bottom Slab

Click this button to open the reinforcement pop-up for the bottom slab.

☐   Single Layer
Check this option to provide single layer of reinforcement to slab of concrete pit.

Size

Select the rebar size for length and breadth directions of bottom slab of concrete pit.
↔ Range: 4 to 50 mm

Spacing

Enter the spacing of reinforcement for length and breadth directions of bottom slab of concrete pit.
↔ Range: 20 to 450 mm (1 to 18 inches)

Top Slab

Click this button to open the reinforcement pop-up for the top slab.

☐   Single Layer
Check this option to provide single layer of reinforcement to slab of concrete pit.

Size

Select the rebar size for length and breadth directions of top slab of concrete pit.
↔ Range: 4 to 50 mm

Spacing

Enter the spacing of reinforcement for length and breadth directions of top slab of concrete pit.
↔ Range: 20 to 450 mm (1 to 18 inches)

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Loads (Top Cover - Monolithic / Non Monolithic Slab)

This page allows to enter the load details for concrete pit and slab.

Live Load on the Slab - LL

Enter the live load intensity over the slab.
↔ Range: 2 to 1000 kN/m² (0.04 to 20 ksf)

Surcharge Live Load - SL

Enter the surcharge live load intensity.
↔ Range: 0 to 1000 kN/m² (0 to 20 ksf)

☐   Water Testing
Check this option to include water testing. On enabling this option, the pit is checked for a case where it is assumed to be filled completely with water.

Loads (Top Cover - Steel Platform)

Live Load on Platform - LL

Enter the live load over steel platform.
↔ Range: 2 to 1000 kN/m² (0.04 to 20 ksf)

Surcharge Live Load - SL

Enter the surcharge live load intensity.
↔ Range: 0 to 1000 kN/m² (0 to 20 ksf)

Steel Platform Self Weight - W_pf

Enter the self weight of steel platform, if top slab is selected as steel platform.
↔ Range: 0 to 1000 kN/m² (0 to 20 ksf)

☐   Water Testing
Check this option to include water testing. On enabling this option, the pit is checked for a case where it is assumed to be filled completely with water.

Loads (Top Cover - Not Present)

Surcharge Live Load - SL

Enter the surcharge live load intensity.
↔ Range: 0 to 1000 kN/m² (0 to 20 ksf)

☐   Water Testing
Check this option to include water testing. On enabling this option, the pit is checked for a case where it is assumed to be filled completely with water.

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Design Setting

Setting for various Design Data such as Soil, Material and Safety Factors are presented in this section. This setting pop-up can be accessed by clicking the bottom panel below the left navigation.

Soil

Unit Weight of Soil - γ_soil

↔ Range: 5 to 50 kN/m³ (30 to 350 pcf)

Unit Weight of Submerged Soil - γ'_soil

↔ Range: 5 to 50 kN/m³ (30 to 350 pcf)

Unit Weight of Ground Water - γ_w

↔ Range: 5 to 50 kN/m³ (30 to 350 pcf)

Allowable Safe Bearing Pressure - SBC

↔ Range: 50 to 500 kN/m² (0.5 to 20 ksf)

Angle of Internal Friction - Φ

↔ Range: 10 to 50 Deg

Reinforced Concrete Properties (BS 8110)

Strength of Concrete - f_cu

↔ Range: 15 to 100 N/mm²

Strength of Reinforcement - f_y

↔ Range: 200 to 600 N/mm²

Density of Concrete - γ_conc

↔ Range: 16 to 30 kN/m³

Modulus of Elasticity of Steel - E_s

↔ Range: 50000 to 300000 N/mm²

Reinforced Concrete Properties (BS EN 1992-1-1)

Density of Concrete - γ_conc

↔ Range: 10 to 40 kN/m³

Modulus of Elasticity of Steel - E_s

↔ Range: 50 to 300 kN/mm²

Compressive Cylinder Strength - f_ck

↔ Range: 15 to 100 N/mm²

Main Reinforcement Grade - f_yk

↔ Range: 150 to 2000 N/mm²

Cement Type - C_type

Select the cement type.

Reinforced Concrete Properties (ACI 318M)

Concrete Type

Select the concrete type.

Density of Concrete - γ_conc

↔ Range: 10 to 40 kN/m³ (60 to 250 pcf)

Modulus of Elasticity of Steel - E_s

↔ Range: 50 to 300 kN/mm² (7000 to 45000 ksi)

Compressive Strength of Concrete - f'_c

↔ Range: 15 to 100 N/mm² (1 to 15 ksi)

Yield Strength of Reinforcement - f_y

↔ Range: 150 to 2000 N/mm² (20 to 300 ksi)

Concrete Modification Factor - λ

↔ Range: 0.75 to 1

Material Factors

Enter the material safety factors on selection of British or European Standard and Design Unit from Design Standard.

Concrete in Compression / Shear / Reinforcement
γ_mc, γ_mcs, γ_ms

↔ Range: 1 to 3

Stability Safety Factors

Uplift - γ_uplifts

↔ Range: 1 to 3

Crack Width

☐   Check for Crack Width
Check this option to include crack width calculation in the design.

Maximum Allowable Crack Width - W_k

Select the maximum allowable crack width value.

National Annex

Select the National Annex after selecting the European Standard in Design Standard.

Nation

Select the National Annex option for the relevant factors to be considered in the design.

α_cc

Enter the value for the User Defined National Annex option. For other options, this is not editable.
↔ Range: 0.7 to 1.2

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Error Handling

Errors and Warnings are generated to prevent any inadvertent error in the input data. This section describes how to handle the errors and warnings. These errors are displayed at the bottom of the input page when the data in one or more input fields invalidate each other.

• Note: Out of range errors are displayed next to the input field.

#	Error	Reason	Solution
1	Warning : Breadth of Pit is exceeding 20000 mm or 800 inches	Breadth of the pit provided exceeds 20000 mm or 800 inches.	Consider the breadth of the pit within the recommended dimension.
2	Warning : Length of Pit is exceeding 20000 mm or 800 inches	Breadth of the pit provided exceeds 20000 mm or 800 inches.	Consider the length of the pit within the recommended dimension.
3	Error : Base of Bottom Slab Level should be Lesser than or equal to Reference Ground Level Elevation	Base of bottom slab level is greater than the reference ground level elevation.	Decrease base of bottom level or increase the reference ground level elevation.
4	Error : Maximum Ground Water Level Elevation should be Lesser than Reference Ground Level Elevation	Maximum ground water level elevation is greater than the reference ground level elevation.	Decrease maximum ground level elevation or increase the reference ground level elevation.
5	Error : Grade Level cannot be above open pit	Grade level is located above top of pit without top slab.	Decrease the grade level or consider top slab for the pit.
6	Error : Grade Level cannot be above pit with Steel Platform	Grade level is located above top of steel platform over pit.	Decrease the grade level or consider top slab over the pit.
7	Error : Thickness of Bottom Slab should be Greater than (2 * Cbslab + Sum of Bottom Slab Bars Dia)	Thickness of bottom slab is inadequate for provided size of reinforcement and cover.	Increase thickness of the bottom slab or decrease the reinforcement size or cover provided.
8	Error : Thickness of Top Slab should be Greater than (2 * Ctslab + Sum of Top Slab Bars Dia)	Thickness of top slab is inadequate for provided size of reinforcement and cover.	Increase thickness of the top slab or decrease the reinforcement size or cover provided.
9	Error : Thickness of Wall should be Greater than (2 * Cwall + Sum of Long wall Bars Dia )	Thickness of wall is inadequate for provided size of reinforcement and cover for short wall.	Increase thickness of wall or decrease the reinforcement size or cover provided for short wall.
10	Error : Thickness of Wall should be Greater than (2 * Cwall + Sum of Short wall Bars Dia )	Thickness of wall is inadequate for provided size of reinforcement and cover for long wall.	Increase thickness of wall or decrease the reinforcement size or cover provided for long wall.
11	Error : Volume of Equipment can not exceed Volume of Pit	Volume of equipment inside the pit provided is greater then the overall volume of the pit.	Decrease the volume of equipment inside the pit or increase the volume of pit.
12	Error : Free Board can not exceed Pit Height	Free board provided is greater than the overall height of the pit.	Decrease free board height or increase the overall height of the pit.