Engineering and architecture are virtually inseparable in the design of tensile structures and Architen Landrell places very high emphasis on design that is functionally driven, believing our structures are all the more beautiful for it.
When integrating tensile membranes within a conventional building envelope the lateral loads transferred can be considerable, as tensile membranes rely on double curvature to resist loads efficiently. Our engineering capabilities provide timely information vital to the overall design process of the load points.
Although most architectural fabrics are barely thicker than 1mm, they are immensely strong and, with careful engineering, are capable of withstanding forces of many tons, which enables them to endure difficult weather conditions under tension. A typical structural fabric would have a tensile strength of 10 tonnes in the fill, and our experience in this field allows us to factor in knowledge such as this throughout the design and planning process.
Canopies fall into two main types: those that transfer tensile loads into adjoining structures and those that contain the tensile loads within their boundary. The first type may generate large lateral loads, which may result in the need for additional reinforcement in existing structures. Likewise a typical ‘lightweight’ canopy with masts and cable tie backs to ground level will generally need significant concrete foundations or screw anchors to resist the tensile loads. Loading analysis derived from a computer model is offered to all clients where it is felt that there is a need, and can give typical loads directions and the size of the design loads. The shape of a membrane surface is determined by the ratio of pre stress in the two principal directions of curvature, established in the computer form generation process. The absolute values of pre stress are calculated to be sufficient to keep all parts of the membrane in tension under any load case.
A frequently asked question is whether tensile fabric structures are suitable for windy sites. The answer is yes as long as the canopy is properly engineered. In the computer analysis of the different load cases, wind uplift is usually as great as the live snow load. The detailing of the fittings and surrounding structure needs to take into account the maximum deflections of the membrane, as well as the loads.
Building in fabric requires no relaxation of structural codes and our engineers ensure that Architen Landrell structures are built to withstand the most onerous conditions. Pre-fabrication of building elements means accuracy is essential, so using 3D CAD modelling is intrinsic to our working method. Visualisation of elements enables clients and design teams worldwide to review our proposals in a ‘virtual studio’, meaning clients and contractors alike have the option of being involved in all aspects of their project.