ASDIP RETAIN is a structural engineering software for design of retaining walls. ASDIP RETAIN includes the design of gravity retaining walls based on the latest ACI 318 provisions. This document is a step-by-step overview of the design of a typical concrete gravity retaining wall example using ASDIP RETAIN.
Gravity retaining wall example
As an example, let’s consider an 8'-0" tall gravity retaining with a flat backfill as shown below. The water table is located 5 ft above the base of the structure. Design the optimum dimensions and find out if an additional footing is required. If so, design the reinforcement, if any.
Gravity retaining wall geometry
In the Geometry tab enter the required stem height as 8′-0″, Initially let's assume a symmetric trapezoidal wall 1'-0" thick at the top and 5'-0" thick at the bottom. No additional footing for now. The geometry will depend on the stability and strength results, so this is an iterative process.
The image below shows the Geometry tab at the left, and a summary view with the most relevant result information in the At-a-Glance tab at the right. Note that the results update automatically with any input changes.
Entering the wall loads
Go to the Loads tab to enter the loads on the wall as defined above. In this example the wall has a 7'-6" flat backfill. Enter the backfill density and internal friction angle and select Coulomb as the lateral soil pressure theory. In addition, specify the water table height as 5'-0". No other loads are acting on the wall.
At this point we can see that the Sliding failure is controlling the design. Let's add a concrete footing under the wall to add more weight to the structure. Let's consider a 1'-0" thick footing with 1'-0" toe and 1'-0" heel. The image below shows the Loads tab, and a view of the Bearing tab with information of the bearing analysis under service loads, for the controlling load combination.
ASDIP RETAIN generates a condensed report in the Condensed tab, showing detailed calculations organized by topic in a tabular format This is excellent for a deeper check of the design as you go.
Specifying the material properties
Go to the Materials tab and specify the material properties as defined above. In this example the concrete strength is 3000 psi. This will affect the shear and moment strengths of the members. In addition, use the Bearing Soil tab to enter the allowable bearing pressure, friction coefficient, and other properties.
The image below shows the Materials tab, and a graphic view the stem pressures and diagrams. Note that the moment and shear diagrams (red lines) fall inside the blue area representing the structural flexure and shear strength respectively. Note that ASDIP RETAIN follows the Strength Design Method of ACI 318 for plain concrete.
ASDIP RETAIN generates a detailed presentation of the results in the Detailed tab, showing step-by-step calculations organized by topic and load combination, with exposed formulas and references to the design code. This is excellent for a deep granular check of the design.
Optimizing the design
As you enter the information, the program calculates the bearing pressure, and it checks the overturning and sliding stability safety factors. If these safety factors are less than the minimum safety factors set in the Design Criteria, then the input values should be modified accordingly. In this example, a wall base 6'-0" thick proved to be adequate.
The shear and moment capacity ratios are unlikely to govern in gravity retaining walls. In this example these two ratios were very small. The footing was not required to be reinforced. The member dimensions were fully optimized.
Takeaway
ASDIP RETAIN includes the design of gravity retaining walls. This step-by-step design example shows how fast the design can be completed and optimized using ASDIP RETAIN. The results are shown instantly in both text and graphics format for an immediate granular check.
For our collection of blog posts about retaining wall design please visit Retaining Wall Design.
Detailed information is available about this structural engineering software by visiting ASDIP RETAIN. You are invited to download the Free 15-day Software Trial or go ahead and Place your Order.
Best regards,
Javier Encinas, PE
ASDIP Structural Software