FAQ

In order to ensure that the results obtained through Structure+ are directly comparable with those implemented in practice, the same FE simulation, material properties, loading conditions and design code requirements are considered for the analysis and design procedures required during the optimization procedure. This is implemented by using the same binary input .SDB (or .EDB) file in the application of Structure+. Therefore, the design requirements that were used to assess the original (reference) design of the user, which was labeled a safe one, are also implemented for all designs generated during the optimization procedure. Consequently, the level of safety of the optimized design is, exactly, the same with that of the original one.

In order to verify that the optimized design is safe (i.e. satisfies all design requirements) the user can use the .SDB (or .EDB) files that correspond to the optimized design and manually perform analysis and design and ensure if there are any error message resulting from the design procedure of SAP2000 (or ETABS).

Structure+ is the result of over 20-years of Research and Development including practical experience in structural analysis and design optimization. Furthermore, the methodologies and advanced algorithms integrated into Structure+ have been validated with the recent publication of the theoretical framework and indicative results in the official Journal of the International Society for Structural and Multidisciplinary Optimization (ISSMO). Structure+ is based on the next generation computational procedures and the implementation of such computing tools is expected to have a profound impact in optimized design of structural systems, leading to revolutionary changes in civil engineering design practice.

The main objective behind the development of Structure+ is to make structural optimization a simple task for structural engineering practitioners. Default values are generated automatically for the parameters required for the solution of the optimization problem making structural optimization a one-click procedure. These options can further be adjusted by the user using the friendly and intuitive interface of Structure+.

The user has the ability to choose, in advance, any section that must not change during the optimization procedure. Furthermore, the user has the option to choose some dimensions of the sections that should not change. For example, in the case of a beam, its height might be preferable to remain unchanged. Structure+ provides the option to the user to ‘lock’ the height of this section and keep it unchanged while the corresponding width can change within specific size bounds.

Indeed, SAP2000 and ETABS perform an optimization-like procedure for the autoselection sections only. The procedure is based on the minimum work concept. However, the resulted design might not be manufacturable; in a sense that it might result to designs where the same structural element is composed by different cross-section along its length, a situation that is neither preferable nor practical. Thus, the grouping per section is lost.

Structure+ can also be considered as a tool for optimizing the topological arrangement of material into the structural system, eliminating the material volume that is not needed or rearranging material volume to locations of increased strength demands. This feature of Structure+ can be used for obtaining smart overdesigned and overengineered designs. Thus, targeting to performance objectives (like maximum drift ratio) the overdesigned and overengineered original user design provided can be, further, improved keeping the same overdesign and overengineer level. Furthermore, the user has the capacity to impose preferences related to overdesigned and overengineered of specific structural elements that can be locked (i.e. their dimensions will remain unchanged during the optimization procedure) through the friendly Structure+ interface.

Structure+ is a plugin to ETABS/SAP2000 and takes into account all regional parameters that are integrated into these products, and as such it can be implemented without limitation world-wide. Structure+’s friendly user interface allows engineers around the world to specify the material cost in relation to the monetary units that are used in the location under optimization.

Both frame and area section modeling approaches are supported by Structure+ and the corresponding structural elements are optimizable. In particular, for area sections (for example, in case of slabs or shear walls), their performance is assessed based on the reinforcement requirements, if a specific threshold (for example 4%) is exceeded then the design is not considered feasible (i.e. that does not satisfy the design requirements).

Structural elements that were assigned to autoselection sections are also optimizable. The section that is assigned to them is selected among the autoselection list that the user created for the specific section type.

Since safety is the primary objective for Structure+, when strength requirements are not satisfied (i.e. strength ratios above one are encountered), then Structure+ will produce the safest design available within the design bounds provided by the user. It is always suggested, that the original (reference) design does satisfy the design requirements. In that case Structure+ will result to an optimized design that will also satisfy the design requirements. In case the reference model violates some of the design checks then the resulting design will possibly also not satisfy some of the design checks, however the strength ratio will be improved significantly; since safety is the major concern for Structure+.

Although, the number of iterations depend on the structural system and the number of sections used for the model, in general around 100 iterations are enough for obtaining an improved design.

Structure+’s advanced interface allows the option to improve the user provided design based on either performance or cost based criteria. For additional information please contact us at [email protected]

Structure+ is the only software world-wide that performs structural optimization studies over the entire structural system taking into account all design load combinations and code requirements. Other solutions might claim they solve structural optimization problems, however, they only perform a per structural member cross-section suggestion.

Structure+ uses the Application Programming Interface (API) that SAP2000 and ETABS provides. This is constantly updated and supported at latest versions only. Hence it is not possible to support older version due to lack of API commands. Going forward Structure+ will be developed and supported on latest versions of SAP2000 and ETABS as new commands, fixes, improvements on the API, developed by CSI are included in latest versions only.

Optimization operations, although can reduce costs considerably, do not decrease the Structural safety. In fact, with this method, surplus materials are eliminated. In most cases, the use of these techniques not only does not undermine the performance of the structure, but also changes the structural load distribution , which will reduce serious damages. At the end of optimization process user get CSI (SAP2000 or ETABS) model of the structure which can tabulate any violation of design criteria.

For each section, defining of related common constraints is prepared and the user can define its project constraints through some forms easily. Nevertheless, customizing of uncommon special constraints is not prepared and you can contact us in proper to developmental your ideal constraints.

We use techniques that usually optimize your structure up to 20%. However, we cannot propose a general value for all types of structures. Because this topic is heavily influenced by the type of structure and first design. For this reason, in some sectors, the payment amount is calculated in terms of the optimized amount of the structure.

Strength , serviceability and ductility criteria derive from the design provisions of ACI 318-08 . Also, geometric constraints are considered that contains dimensional limits for beams and columns, minimum and maximum area of longitudinal reinforcements and some constructional criteria for connections.

Flexural, shear and torsional reinforcement is considered based on a program analysis results for beams and defined section for columns..It may increase after detail design related to rebar anchor, development length and cover system.

According to the ASCE7-16,the story drifts are computed as the difference of the lateral load deflections at the center of mass between the two story (for regular structures). Although the analytical period for each structure can be considered for calculating lateral load, but this feature is not considered and lateral load is considered fixed.For SAP2000 model the points (center of mass) must be assigned in a group (Group-Disp) and drift is controlled only for these points.