Vespa MSE (Mechanically Stabilized Earth) Design Software is different. Created by experts in MSE design, Vespa saves time by automating processes currently done manually, and by integrating the design and drawing process.
MSE Structures
Compared to existing MSE Design Software options, Vespa increases design efficiency, improves accuracy, and promotes a seamless flow of information between design stages and parties. Vespa allows the user to import grading and layout information directly from CAD using a CAD routine called AWall that is included with the Vespa Software package. The AWall CAD routine allows the designer to lay out the proposed wall right on the CAD grading plan to show accurate plan views of the wall, and then can export the wall geometry to Vespa. Once the wall geometry is imported or manually input, the user can then design walls using ANY user input or Vendor supplied Modular Block/Geogrid combination. Marshall amplifier service manual pdf power.
Vespa then generates full wall layouts with accurate quantity estimates and comprehensive reports. The Vespa Calculation Engine can simultaneously run Static, Seismic, and ICS Analysis in accordance to NCMA or AASHTO (LRFD) Design Methodologies. Vespa MSE Design Software is built around the understanding that the goal of the Design Engineer is to produce a set of clear, comprehensive construction drawings. That’s why Vespa automatically generates CAD cross sections and elevation views of the walls you’ve just designed. Once the design is complete, Vespa also allows you to export the wall geometry, soil conditions, and loading conditions to select Global Stability software programs.
Vespa MSE Design Software helps put all parties on the same page and all the pieces of the design puzzle together. For the MSE Designer, the real time savings you gain using Vespa can pay for itself on the very first project.
A few customers have requested implementation of the K-stiffness Method in program MSEW. Although such implementation in the framework of MSEW is simple, we do not plan to perform the task since the current method appears to be invalid, very possibly rendering unsafe results. The reasoning behind this conclusion is the formulation of the K-Stiffness method, which is a statistical analysis based on a compilation of field data of retaining walls from various, unrelated researchers. The formulation is not based in physics or statics, but in statistics, ignoring long term design stability essential to the safe function of a structure. The approach empirically links stiffness, spacing of the reinforcement layers, facing properties, batter, and shear strength of the soil using little more than statistical correlations. Thus, the method ignores the vital inclusion of statics in design for the sake of rendering less conservative reinforcement tensile forces that are scientifically unsubstantiated over the long-term. Seasoned engineers would and should be skeptical about the feasibility of such statistical shortcuts.
The field data that serves as a foundation for the K-Stiffness formula, deemed as a comprehensive basis for solutions, was very likely for situations where soil matrix suction rendered apparent cohesion. Cohesion reduces or even eliminates the reinforcement load; however, apparent cohesion is dependent on moisture content (or degree of saturation of soil) and should not be counted on in design as its value may periodically diminish over the life of the structure. In fact, the K-stiffness method ignores the apparent cohesion in its statistics (the magnitude of this cohesion is impossible to determine in-situ) and, essentially, attributes the low ‘measured’ force in the reinforcement to what amounts to “magic.” That is, the method bypasses basic statics, ignoring simple global equilibrium in favor of uncritical acceptance of field data combined with statistics, and gives no scientific justification for the lower tensile forces. Indeed, apparent cohesion may render reinforcements dormant, but when the cohesion vanishes, the reinforcement will be activated and failure may occur. The issue of dormant reinforcement due to apparent cohesion is explicitly described in: Leshchinsky, D., “Geosynthetic reinforced walls and slopes: Is it magic?” Geosynthetics Magazine 28(3), 2010, 17-24.
The indications that suggest current design is conservative do not transitively imply that the remedy offered by the K-stiffness Method is correct. In fact, without a mechanistic benchmark, its use may lead to overly reduced conservatism, an unsafe conclusion that could result in failure.
A considerable amount of additional material relevant to this issue is published in refereed engineering journals, including:. Leshchinsky, D., “On Global Equilibrium in Design of Geosynthetic Reinforced Walls,” ASCE, Journal of Geotechnical and Geoenvironmental Engineering, 2009, 135(3), pp. Leshchinsky, D., Zhu F., and Meehan, C.L., “Required unfactored strength of geosynthetic in reinforced earth structures,” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2010, 136(2), 281-289.
Leshchinsky, D., Imamoglu, B. And Meehan, C.L., “Exhumed geogrid-reinforced retaining wall,” Journal of Geotechnical and Geoenvironmental Engineering, ASCE, 2010, 136(10). Please contact for any information.
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