ASDIP RETAIN is a structural engineering software for design of retaining walls. ASDIP RETAIN includes the design of concrete cantilever retaining walls based on the latest ACI 318 provisions. This document is a step-by-step overview of a design example of a typical concrete cantilever retaining wall using ASDIP RETAIN.
The design of retaining walls may become cumbersome and time-consuming, since it involves an iterative process to calculate the stability ratios, and the application of the Code provisions to design the reinforcement.
Cantilever retaining wall design example
As an example, let’s consider a cantilever retaining with a flat backfill, subject to the surcharge load shown below. The water table is located below the base of the structure. Design the optimum dimensions and find the required reinforcement.
Cantilever retaining wall geometry
In the Geometry tab enter the required stem height. From the given information, the total wall height is 18′-0″, so it’s necessary to assume a footing thickness. Let's set an initial value of 18". The toe and heel lengths 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 full height backfill, and a uniform dead surcharge on top. Enter the backfill density and internal friction angle and select Coulomb as the lateral soil pressure theory.
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 strength and will control the thickness of the stem and footing.
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.
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 NDS code. This is excellent for a deep granular check of the design.
Specifying the reinforcement
Go to the Reinforcement tab to specify the rebars for the wall. ASDIP RETAIN has multiple options to customize the reinforcement. In this example, we specified stem bars #8 @ 10" and footing bars #7 @ 12" top and bottom.
The image below shows the Reinforcement tab and a construction view of the final retaining wall design example rebar sizes and spacing.
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 toe length of 4.00 ft and a heel length of 5.00 ft proved to be adequate.
The shear capacity ratio will govern the thickness of the different elements. In this example a stem thickness of 18" provided a shear ratio of 0.92. The footing thickness was controlled by the heel. A footing thickness of 24" provided a shear ratio of 0.98. The member dimensions were fully optimized.
Please note that the structural capacity from the specified reinforcement provided utilization ratios of 0.95 and 0.92 for the moment and shear diagrams respectively. This indicates that the design fully utilized the structural capacity.
Takeaway
ASDIP RETAIN includes the design of cantilever 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
Want to see software for counterfort retaining wall.
ASDIP Retain 4 will be out in March 2018. It will include counterfort retaining walls. Regards.
does asdip have choice for other codes e.g eurocode,british code?
This version is based on the american standards: IBC, ACI, MSJC. Future versions will include other design codes.
Thats great apps so ill need for in general structural building deaign. From dounsation up to structural component