Once the pressure distribution has been calculated, the designer can determine the required sheet length and possible wale placement by balancing the passive and active pressures and rotational forces. There are several methods commonly used for analyzing the rotational stability of the wall. The two most commonly used methods are:

· The Free Earth Support Method
· The Fixed Earth support Method

It is often desirable to attempt several iterations of the rotational stability calculations with different sheet length and wale placement scenarios in an effort to find the optimal solution. The rotational stability analysis methods can then be used to determine suitable anchor placement behind the structure. Anchor placement and sheet length/ penetration are the most commonly overlooked design parameters and need to be considered very carefully by the designer in order to ensure adequate global stability of the structure.

The next step in the engineering analysis is to calculate the maximum bending moment induced in the sheet piling associated with the calculated loading conditions. The loading configurations for a sheet piling wall are often much more complex than those usually seen in standard engineering beam analyses, however the maximum moment can still be calculated by summing moments and forces in conjunction with the previously listed pressure distribution and rotational stability analysis methods.

Because of the relative flexibility of vinyl and composite sheet piling, classical calculations tend to be conservative, as generally, the bending moment decreases with increasing flexibility of the sheet piling. The effects of sheet piling flexibility on moment reduction are due to many factors including soil relaxation and are well documented. It is therefore recommended that the designer use a more realistic model when determining induced bending moments such as that produced by Rowe's Moment-Reduction Method.

There are an extensive amount of engineering textbooks and resources that cover the fundamentals of engineering analysis for sheet piling structures. It is recommended that the designer refer to one that they may be familiar with during the engineering analysis process.

The Foundations and Earth Structures Design Manual 7.2, Department of the Navy, Naval Facilities Engineering Command is widely used in industry for guidance and methodology of the engineering analysis of sheet piling structures.

Several computer-modeling programs are available for the evaluation of sheet piling structures. These tools allow the designer to quickly evaluate "what if" design alternatives and greatly reduce computation time when compared to hand calculations.

Your project specification is the most critical factor in ensuring the actual performance of the sheet piling you are choosing is appropriate for your particular application.

The best way to make sure that all products being bid or considered for your project are appropriate (and you are getting the most economical solution), is to write a performance-based specification. A performance-based specification lays out the specific performance requirements needed for your particular application, as opposed to a product specification which lays out the published specifications of a particular product. It is always wise to let your project parameters, goals, and design dictate the specification rather than what a particular supplier may tell you they think you need. Always pay particular attention to actual and overall product performance parameters that you need in the field and not small scale theoretical design values that may be pushed by a material supplier.

Your specification should be open to any product as long as it meets all of the parameters that are important to your project. This will allow you to get a product that meets all of your real project parameters and requirements at the best cost level possible.

The first step in your specification writing process is to determine which performance factors are critical to your project and to prioritize them. Some of the most common performance factors are:

· Sheet piling material selection (vinyl, composites, steel, etc.)
· Material quality (source of material, consistency, durability, weatherability, etc.)
· Material performance (mechanical properties, weatherability, chemical resistance, etc.)
· Product aesthetics (color consistency, overall appearance, etc.) Product structural performance (allowable moment, stiffness, ductility, etc.)
· Installation performance (driveability, impact strength, stiffness, etc.)
· Chemical resistance Transmissivity
· Product cost and budget
· Manufacturer performance (experience, ability to deliver on time, credibility, etc.)

Once your performance parameters are selected qualitatively, it is time to set specific and measurable levels for each requirement. For your own best interest, make sure that the numbers you select for performance requirements are determined based on what your project requires and not just one particular product. This will allow you to find the most competitively priced product that meets all of your site specific performance criteria.

The specification template given in the next section is intended to be used as a starting point and a guide to help you through the specification writing process. Take whatever performance criteria you have deemed required and set quantitative performance levels. Remove any sections that are not important for your project and add any other specifications or criteria that you may deem appropriate.