Labor and Material Savings Are Key to Optimization and Customer Value
Assembly testing is performed to better understand interacting parts and pieces and determine whether they are really needed to resist applied loads. The only way to have a complete understanding of performance is by applying loads to an assembly that is sitting on load cells. This allows that load to be traced as it migrates through the assembly. This information is then used to make a wide variety of engineering judgements. This is engineering as an artform.
Mechanics of Material Understanding
This slide shows both the predicted stresses and actual stress fractures in the concrete layer as tested. Qualtim’s FEA model predicts about 3,000 psi for mortar cracking to occur. Tesing confirms that concrete cracking and spalling does occur at this stress level. This confirms and calibrates the Qualtim FEA model to be used to undertake load path resistance design more precisely.
Qualtim FEA Model Calibration
Calibrating the Qualtim FEA model has to be done under a variety of applied load and resistance conditions. The goal is to verify its design applicability to the variety of potential engineering boundary conditions and limit states that need to be considered in building design. The goal here was to challenge the Qualtim FEA model on its prediction. At 58,000 pounds this stress crack formed = confirmation.
Composite Product Evaluation
A composite concrete element is complex. There are direct compression, tension, bending and shear stresses that need to be addressed as previously shown. From there a key question is: does the FEA model predict combined stresses well? In this case the applied 40,000 pound load created a combined bending shear failure mode which was compared to the Qualtim FEA prediction.
Load Deflection Performance
Calibration of design load deflections is challenging due to the concrete cracking. Applying loads in steps and comparing the load-deflection plots to the Qualtim FEA load-deflection plots provides the benchmark data. Using the similarities and differences allows judgements to be made with respect to the effect of concrete cracking and adjustments to the composite stiffness (EI) used in the model so accuracy is maintained.
Non-linear Analysis and Calibration
Composite beam applications require testing and FEA calibration using non-linear methods. The best way to do this is to test beams and genate their load deflection behavior. From this data an FEA model for the composite section can be created. The plot of the FEA model against test data provides FEA counsel with respect to FEA model adjustments.