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Fabric is only as good as the structure under it

When designing fabric structures it is critical to take into consideration the strength and design of the building as a whole. At Calhoun we apply our unique 3D Nonlinear Finite Element Analysis to engineer our fabric structures site-specific to suit our customers’ unique locations.

Reputable fabric structures companies will work with their network of sales teams or dealers to obtain site photos and site topography with the orientation and location of the marked building. This allows the fabric structure’s engineers to begin the process of evaluating the site conditions. The site evaluation ensures that the appropriate parameters are used for the analysis of the structure. The configuration of the building is thereby validated, or changes are made to ensure the structure has the requisite reliability for the site. A fabric structures company should use external, third-party engineers to review all structures to avoid company bias and ensure the strict objectivity of the design work.

All of Calhoun’s fabric structures are reviewed by independent third-party structural engineers. Watch our video to learn more about Calhoun’s unique site-specific review that no other fabric structure manufacturer in the market employs.

Our Propietary Engineering Process

Through our proprietary engineering process we model the true behavior of fabric relative to environmental factors using our unique 3D Nonlinear Finite Element analysis. Our method produces the most suitable fabric structures to meet your requirements, resulting in a quicker return on your investment and the longest-standing structure in the industry.

During the course of each and every site-specific analysis, a complete 3D nonlinear analysis providing accurate load paths to, and forces at, foundation-resisting elements is completed. Due to the fact that the fabric structures rely primarily on tension only bracing for stability, the pre-tension in the cables and initial inelastic stretch is critical to the performance of the structure. The pre-tension requirements and procedure for initial pre-tension and proof loading are determined through the nonlinear analysis.

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CALHOUN’S ENGINEERING METHODS ENSURE STRUCTURAL INTEGRITY

A comprehensive 3D nonlinear analysis is essential to provide guidance in the design of highly reliable and economic foundation systems. In situations where an even higher degree of economy is desired, the foundation wall supported on soil springs may be modeled explicitly in conjunction with the fabric structures such that the interaction between the two can be appropriately addressed wherein the resulting concrete stresses may be used to determine the concrete wall thickness and spacing for reinforcement. 

This frequently leads to as much as a 40% increase or more in foundation economy with a considerable improvement in overall reliability of the system given the fabric structures and foundation interactions including bearing pressures beneath the wall footings are appropriately addressed in a comprehensive analysis. Overall, the primary objective of the 3D nonlinear analysis is to provide clear prescriptive recommendations for the structural integrity and limitations of the structure under various code specified load conditions.

Detailed Wind and Seismic Analysis

For each and every site-specific analysis, a comprehensive seismic analysis is completed which includes the modal response behavior of the building and the building’s actual fundamental period. This analysis is also used in the wind design to ensure that the period of the structure will not substantially affect the behavior of the structure during a design wind event.

Fabric Stresses & Scaled Displacement

During a nonlinear analysis, the load is discretized and applied in steps. If an element is set as tension only (cables, fabric etc.), the program iterates further during each of the specified iterations until all of the tension only elements are in tension or have zero force. Afterwards the displacements and internal forces are used as the starting point for the next iteration and the process is repeated until the specified number of load steps is completed for each of the code specified load combinations.

Buckling Analysis

During the course of each and every site-specific analysis, a buckling analysis is completed at minimum for each of the controlling load combinations. This analysis goes to ensure that the assumptions for the effective length estimates used to identify in the mass checks the critical members for detailed checks are suitable for the actual site-specific conditions and whether or not second order effects are a consideration in the design.