Phi and psi can be viewed in the Rama map tool in Foldit. The critical backbone angles named phi and psi are determined relative to the alpha carbon. The alpha carbon connects the following parts of the amino acid: The alpha carbon (atom 2) is the central feature of the backbone. Except for the ends of a protein chain, the backbone of each segment contains the same atoms. Strong peptide bonds join the segments, forming the backbone. Switching to a view like "Stick + Polar H" and using EnzDes or CPK coloring reveals more about the backbone.Įach segment of a protein is the residue of an amino acid.
The "cartoon" views in Foldit show the shape of the backbone, but hide most of the chemical structure. Protein sidechains receive most of the attention, but understanding the backbone is also important in Foldit. (Compare the backbone shown here to RNA backbone, which has over twice as many atoms.) Protein backbone is what holds a protein together and gives it an overall shape (or tertiary structure).Ĭompared to RNA and DNA backbone, protein backbone has a relatively simple chemical structure - a nitrogen atom, two carbon atoms, one or two oxygen atoms, and a few hydrogens. Here, a methionine sidechain is attached to the alpha carbon of the segment in the center. Peptide bonds join the carboxyl group of one segment to the amino group of the next.
#BACKBONE DEFINITION FULL#
In addition, the experiments demonstrate the large difference between idealized engineering models of the seismic force-resisting system and the superior performance of the full building system.Protein backbone features. The research provides the necessary building blocks for developing efficient nonlinear time history models of buildings framed from cold-formed steel. Major deliverables in the CFS-NEES effort included: shear wall testing, characterization, and modeling cyclic member testing, characterization, and modeling and, whole building shake table testing, and modeling. Recently, a North American effort under the abbreviated name: CFS-NEES has begun to address this challenge head on. As a result, seismic performance-based design has also remained out of reach for cold-formed steel framed buildings. In the past, testing on individual shear walls has been used to provide insights and create safe seismic designs for cold-formed steel buildings, but understanding and modeling of whole buildings have been out of reach. Significant research has been conducted on individual cold-formed steel members, but little research has been done on full buildings framed from cold-formed steel.
This paper demonstrates that the proposed modelling method not only saves analysis time considerably through the drastic reduction of degrees of freedom, but also compares favourably against a published modelling method in terms of accuracy and modelling efforts.īuildings framed from cold-formed steel members are becoming increasingly common. The resulting two-storey building model, which has much fewer degrees of freedom compared to conventional models, is verified against full-scale shake table test results with respect to the natural period, the peak storey drift and the peak floor acceleration at two different construction phases. The equivalent shear modulus is determined from the experimental test of a representative wall panel, or from the analysis of a finely detailed finite element model of the panel. Each shear or gravity wall is represented by an equivalent shear modulus four-node orthotropic shell element, which incorporates the lateral stiffness (or flexibility) contributions of all components including sheathing, braces and fasteners as present in the wall. This paper proposes an efficient modelling method that enables practical and accurate 3D elastic analysis of a multi-storey CFS building structure to study its lateral behaviour within the serviceability limit state. They are therefore commonly ignored in a 3D structural analysis, and their benefits are lost to the design. Non-structural components contribute significantly to the lateral stiffness of a cold-formed steel (CFS) building structure, but are cumbersome to model explicitly in the structural analysis.
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