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Data Security Notice Updated 27th February 2020

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Website Terms and Conditions

The contents of this web site are protected by copyright and other intellectual property rights under international conventions. No copying of any words, images, graphic representations or other information contained in this web site is permitted without the prior written permission of the webmaster for this site.

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Software Licensing Terms

Terms and Conditions of Purchase

The full conditions of purchase and maintenance for all Oasys desktop software are set out in the Oasys Software Licence and Support Agreement.

The full conditions of purchase and maintenance for Oasys Gofer and Oasys Giraphe are set out in the Gofer SaaS Agreement  and the Giraphe SaaS agreement.

All prices are subject to TAX at the current rate.

Prices and specifications are subject to change without notice – please ask for a written quotation.

Although every care has been taken to ensure the accuracy of all information contained herein, the contents do not form or constitute a representation, warranty, or part of any contract.

Superseded Versions of Terms and Conditions

Oasys keeps copies of all superseded versions of its terms and conditions.

Maintenance & Support Services

Support and maintenance is included with all subscription licences for their full duration.

Annual maintenance contracts are available for software under a perpetual licence, prices are based on a percentage of the most recent list price.

This service includes:


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Optimisation of High-Rise Structures

Software Used on this Project

Project Overview

In order to optimise the freeform truss façade of their high-rise structure in the early stages of the design process, Bas Wijnbeld at the Eindhoven University of Technology, working with the Arup Amsterdam office, knew that they could combine their creative programming skills with the power and flexibility of GSA to achieve the desired result. Their optimisation tool, which makes extensive use of the COM interface possibilities of GSA, has two principle functions. The first is to generate a single structure based on user-defined parameters. It then finds the minimum section sizes that satisfy the strength and stiffness requirements. The second principle function is to use artificial intelligence techniques to determine the optimal structure.

The basic inputs of the optimiser program are:

  1. The boundary of each floor. This determines the shape of the building
  2. Initial section sizes
  3. Dead, live and wind loads

How Oasys proved invaluable

How does it work?

The optimisation tool was developed using just Visual Studio and the GSA COM-interface. GSA’s role was both visualisation and analysing the generated structural models, supplying the results back to the optimiser program.

Generating the Geometry

First the optimiser program reads node and element data from the initial GSA model and uses this information to recognise floor edges. As this optimiser program is especially developed for freeform continuous smooth surfaces it doesn’t recognise corners; an optional subdivision algorithm can be used to increase smoothness of the floor perimeters.

The next stage is to decide the locations of the floor connections, resulting in elements being created between these nodes.

Creating a Complete Calculation Model

As a calculation model needs more than the geometry alone; the section properties, con

straints, releases, loads and load combinations are also generated. In this example there are a total of 30 load combinations: 9 SLS combinations and 21 ULS combinations.

Just like the node and element data, all this information is easily exported by using the GwaCommand function of the COM-interface.

Steps generating a model

Optimising Section Sizes

The minimal needed section sizes are automatically determined from both the strength and stiffness constraints. This process is split in two steps: first the minimal needed section sizes based on strength are determined (Eurocode check). This is a simple process, where the section sizes are iteratively changed based on the forces in that element: the model is calculated in GSA and the forces acting on each element are exporting to our program which determines the minimal needed section size. As changing the section size changes both the self weights and stiffnesses, hence force distribution, this process repeats until it converges on the overall lightest sections.

After the minimal section sizes are determined based on strength properties, the top and storey drift has to be limited to a maximum set by the user. To do this efficiently, a sensitivity analysis is performed: for every section group the effect of this section size on the deformations is considered. With this information and the steel weight of every section group (which the GSA can export using the COM), the most economic decision can be made.

Section distribution for different (non-optimised) models

Finding the Optimal Topology

Process of a Genetic Algorithm

The final task of the program is to find the optimal topology of the truss façade structure. Optimal is in this case defined as: minimal weight and minimal elements (nodes). Because the solution with the minimal weight generally isn’t the solution with the minimal elements, this results in a range of solutions which are optimal in a certain way; this range is known as the Pareto Front. The Pareto front is found by using the Harmony Search Algorithm (comparable to a Genetic Algorithm), with three populations (each with a different target) and containing 10 possible solutions each. In total around 1,000 possible solutions are generated and optimised in every single cycle.

This process would be virtually impossible without stability and robustness of GSA and especially its COM interface while conducting heavy computation.

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