CONNECT Licensing

ACI 318-2014

For the foundation types in the General Mode and Plant Mode of the program for which design per the ACI 318 code is available, the 2014 edition of the code has been implemented. Those types include isolated footings, combined footings, pilecaps, mat foundations, strap, horizontal vessels (heat exchangers), etc.

This edition can be selected at the time of creating a new job, or editing an existing job. See the following figure.

In terms of functionality, all the checks that were performed by older versions of this code are performed by this edition too. This includes checks such as one-way shear, punching shear, flexure, development length, etc.

The code name and year will be displayed at the top of the calculation sheet.

The equations of that code used in the calculations for the various checks are displayed in the calculation sheet.

The 2014 edition of the code is not yet available for the foundation types in the toolkit mode.

Utilizing Passive Pressure Resistance in Overturning and Sliding Checks

For isolated footings, the resistance offered by passive pressure of soil to lateral forces and overturning moments can now be considered in the stability calculations.

See Utilizing Passive Pressure Resistance in Overturning and Stability Checks for details on how the program calculates this and the parameters to utilize this feature.

Pedestal Design per Eurocode 2 for Isolated Footings

For isolated footings, design of the pedestal is now performed per the EC2 code BS EN-1992-1-1: 2004 with the British Annex.

See Pedestal Design per Eurocode 2 for Isolated Footings for details on how the program performs pedestal design per EC2.

Soil Excavation Volume and Backfill Volume

For isolated footings designed to ACI 318, STAAD Foundation Advanced now reports the following quantities:

1. Soil Excavation Volume

   This is the volume of soil contained in a pit that must be dug before the foundation and pedestal can be cast. In the following figure, it is represented by the container with the blue colored walls.

   

   The top of the container is the ground level.

2. Soil Backfill Volume

   This represents the volume of soil that must be poured back in the pit after the footing and pedestal are cast. It is numerically equal to the soil excavation volume minus the volume of concrete contained in the footing and pedestal. Only the portion of the pedestal between the ground level and the top of footing is considered in the concrete volume quantity calculation.

   The soil excavation volume is calculated in the following manner.

   

   Cross section of the excavation

   The pit is assumed to be a trapezoidal prism (a frustum of a pyramid) whose characteristics are:

   • base (bottom of the pit) is rectangular having dimensions (L+2s) and (B +2s)
   • where "s" denotes a side distance between the bottom edge of the pit and edge of the footing
   • top (top of the pit) is rectangular having dimensions (L+2s+2e) and (B+2s+2e)
   • where e = slope of the sidewalls of pit x depth of the pit
   • If we define A1 = (L+2s) × (B +2s)
   • and A2 = (L+2s+2e) × (B+2s+2e)
   • then, soil excavation volume $\frac{1}{3}\times (h+t)\times (A1+A2+\sqrt{A1\times A2})$
   • where “h” = height of soil above footing
   • t = thickness of the footing
   • h+t = depth of the pit

   The following information is presented in the calculation sheet:

   

   "a" and "b" are terms defining the slope of the side walls of the pit.

   In the present version, the term "s" is assumed to be 0.0, and the slope a/b is assumed to be 1.0. In a future release, the feature will be enhanced to allow user-defined values for these terms.

Utilizing the Cohesive Strength of Soil for Resistance to Sliding and Overturning

In the topic titled Utilizing Passive Pressure Resistance in Overturning and Stability Checks, it was shown how the passive resistance offered by the soil can be used to augment the capacity of the foundation to resist sliding and overturning.

For isolated footings designed to the Indian code, the resistance offered by the cohesive strength of soil to lateral forces and overturning moments is another option available (in addition to passive resistance) to augment the resistance. This too is an optional item, meaning, the engineer is given a choice as to whether you want to include this resistance.

Refer to Utilizing the Cohesive Strength of Soil for Resistance to Sliding and Overturning for additional details on how this resistance is calculated and how to use it for the design of isolated footings per the Indian code.

Miscellaneous Changes

The enhanced shear capacity of concrete, for computation of shear strength of concrete in various foundation types designed per the Indian code, is now an optional item. By default it is not used, but if the engineer wants it to be used, it should be switched on from Global Settings as shown below.

Rectification of Defects

A number of improvements have been made in the program in areas such as handling of input, removal of defects in calculations for some of the foundation modules, display of output, printing, drawing generation, stability related aspects that resulted in crashes or caused the program to freeze, extensive time taken for analysis of certain modules, etc. For details, see the Revisions History page.