Characterizing the Load Deformation Behaviour of Steel Deck Diaphragms

Lateral loads flow through a building’s horizontal roof and floor diaphragms before being transferred to the vertical lateral force resisting system (e.g. braced frames, moment frames or shear walls). These diaphragms are therefore a critical structural component in the resistance of lateral loads. A review of the literature shows that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck and concrete on steel deck diaphragms. The tested diaphragm behavior was found to be dependent on a set of factors including loading protocol, fastener type, fastener size and spacing, and more. There does not currently exist a single, unifying review of these diaphragm tests and their relevant results. A research program is being conducted to collect and consolidate the available literature about tested steel deck diaphragms and their results. A database has been created that includes over 450 tested specimens with more than 130 cyclic tests. In addition, an effort is made to characterize diaphragms’ load-deformation response as grouped by sidelap and support fastener type. The test programs and results collected into this database as well as the characterization of diaphragm behavior are discussed in this paper

Local Buckling Hysteretic Nonlinear Models for Cold-Formed Steel Axial Members

This paper studies the energy dissipation and damage in thin walled members that experience local buckling and presents an approach to model cold-formed steel (CFS) axial members that experience local buckling deformations. The model is implemented in OpenSees using hysteretic models for CFS axial members calibrated using experimental responses. Results from thin-shell element simulations using ABAQUS show that energy dissipation in thin plates dissipates through inelastic strains and yielding that concentrates in damaged zones that extent approximately the length of a buckled half-wave (Lcr). Generally damage accumulates in one zone but when more than one damaged zone occurred the energy dissipation increased proportionally. The results from the plate simulation and experimental results from cyclic tests on axially loaded CFS members (previously performed by the authors) support the assumptions for the modeling approach presented for CFS members governed by local buckling. Results demonstrate the capabilities of the modeling approach to efficiently and accurately simulate the response of the CFS axial members experiencing local buckling. The model presented can be used to facilitate the performance assessment of cold-formed steel lateral load resisting systems (e.g., shear walls) under different hazard/performance levels, a capability needed for the advance of performance-based earthquake engineering of cold-formed steel buildings

Characterizing the load-deformation behavior of steel deck diaphragms using past test data

Recent research has identified that current code level seismic demands used for diaphragm design are considerably lower than demands in real structures during a seismic event. However, historical data has shown that steel deck diaphragms, common to steel framed buildings, perform exceptionally well during earthquake events. A new alternative diaphragm design procedure in ASCE 7-16 increases diaphragm seismic demand to better represent expected demands. The resulting elastic design forces from this method are reduced by a diaphragm design force reduction factor, Rs, to account for the ductility of the diaphragm system. Currently, there exist no provisions for Rs factors for steel deck diaphragms. This research was therefore initiated to understand inelastic steel deck diaphragm behavior and calculate Rs factors. A review of the literature showed that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck diaphragms. To unify review of these diaphragm tests and their relevant results, a database of over 750 tested specimens was created. A subset of 108 specimens with post-peak, inelastic behavior was identified for the characterization of diaphragm behavior and ductility. A new recommended method for predicting shear strength and stiffness for steel deck diaphragms with structural concrete fill is proposed along with an appropriate resistance factor. Diaphragm system level ductility and overstrength are estimated based on subassemblage test results and Rs factors are then calculated based on these parameters. The effects of certain variables such as deck thickness and fastener spacing on diaphragm ductility are explored.American Institute of Steel Construction (AISC), American Iron and Steel Institute (AISI), Steel Deck Institute (SDI), Steel Joist Institute (SJI), Metal Building Manufacturers Association (MBMA), National Science Foundation (NSF

SDII Building Archetype Design v1.0

Building archetypes are fundamental to exploring and demonstrating the seismic behavior of modern structures. No suitable archetypes or prototypes exist in the open literature that focus on steel deck diaphragms for conventional steel buildings. Three dimensional building analysis, with meaningful contributions from the diaphragm in terms of behavior, has not formed the basis for modern seismic standards in steel at this time. The objectives for the SDII building archetypes include the following. Develop a series of 3D steel-framed archetype buildings that explore and document the design of horizontal lateral force resisting systems (LFRSs) with steel deck-based diaphragms as well as vertical LFRSs and the inter-relationship between the two. Provide a series of buildings that form a common basis of comparison for diaphragms in steel-framed buildings much the same way the SAC buildings did for the vertical LFRS. Explicitly explore the impact of the ASCE 7-16 standard, and ASCE 7-16 alternate diaphragm design with Rs=1 and Rs=3 in designs. Inform areas for needed experimentation, and create targets for advancing nonlinear analysis within the full SDII effort. Version 1.0 of this archetype effort includes: (1) a complete slide deck explaining the design of a 12 story steel building archetype using buckling restrained braced (BRB) frames for the vertical LFRS and steel deck with fill for the diaphragm/horizontal LFRS detailed to the ASCE7-16 standard as well as the ASCE7-16 alternate diaphragm provisions with Rs=1 and Rs=3, (2) a series of spreadsheets that provide the complete design calculations for the gravity and lateral systems, (3) a series of computer models (using the SAP structural analysis program), and (4) a literature review of other related building archetypes and justification for developing new building archetypes. (This version has been superseded by v2.0 - see http://jhir.library.jhu.edu/handle/1774.2/62106)American Institute of Steel Construction (AISC), American Iron and Steel Institute (AISI), Steel Deck Institute (SDI), Steel Joist Institute (SJI), Metal Building Manufacturers Association (MBMA), National Science Foundation (NSF

Sidelap and Structural Fastener Tests for Steel Deck Diaphragms

Steel deck diaphragm systems, which are commonly used for roof construction in steel-framed buildings, consist of many parts such as corrugated steel deck sheets, sidelap fasteners between adjacent sheets, structural fasteners from the sheets to the supporting beams or joists, chord elements, and collectors. Load-deformation behavior of a steel deck diaphragm system is typically dominated by sidelap and structural fastener limit states. To understand and accurately model the behavior of steel deck diaphragm systems, it is therefore necessary to characterize the behavior of the individual fasteners. The effect of local geometry and detailing at these fasteners such as how the sheets fit together, fastener proximity to the sheet edge, and fastener location relative to the corrugation is not well understood. This paper presents a testing program including 80 specimens with single fasteners in flat steel deck sheets (not corrugated) that remove the effects of corrugation and edge distance. The testing program included two types of sidelap fasteners (#10 screws, #12 screws), four types of structural fasteners (powder actuated fasteners, pneumatic power actuated fasteners, arc seam welds, #12 screws), as well as other variations such as number of deck plies for structural fasteners (1 ply to support, 2 ply, and 4 ply), deck thickness (22 gage, 20 gage and 18 gage), and loading (monotonic and cyclic). A companion suite of 60 monotonic and cyclic tests were conducted with deck geometry and detailing representative of typical construction. By comparing results between these two sets of tests, the effect of deck geometry and fastener location was isolated

Characterizing the load-deformation behavior of steel deck diaphragms using past test data

Recent research has identified that current code level seismic demands used for diaphragm design are considerably lower than demands in real structures during a seismic event. However, historical data has shown that steel deck diaphragms, common to steel framed buildings, perform exceptionally well during earthquake events. A new alternative diaphragm design procedure in ASCE 7-16 increases diaphragm seismic demand to better represent expected demands. The resulting elastic design forces from this method are reduced by a diaphragm design force reduction factor, Rs, to account for the ductility of the diaphragm system. Currently, there exist no provisions for Rs factors for steel deck diaphragms. This research was therefore initiated to understand inelastic steel deck diaphragm behavior and calculate Rs factors. A review of the literature showed that a large number of experimental programs have been performed to obtain the in-plane load-deformation behavior of steel deck diaphragms. To unify review of these diaphragm tests and their relevant results, a database of over 750 tested specimens was created. A subset of 108 specimens with post-peak, inelastic behavior was identified for the characterization of diaphragm behavior and ductility. A new recommended method for predicting shear strength and stiffness for steel deck diaphragms with structural concrete fill is proposed along with an appropriate resistance factor. Diaphragm system level ductility and overstrength are estimated based on subassemblage test results and Rs factors are then calculated based on these parameters. The effects of certain variables such as deck thickness and fastener spacing on diaphragm ductility are explored.American Institute of Steel Construction (AISC), American Iron and Steel Institute (AISI), Steel Deck Institute (SDI), Steel Joist Institute (SJI), Metal Building Manufacturers Association (MBMA), National Science Foundation (NSF

Realisation of small molecule libraries based on frameworks distantly related to natural products

The availability of high-quality screening compounds is of paramount importance for the discovery of innovative new medicines. Natural product (NP) frameworks can inspire the design of productive compound libraries. Here, we describe the design and synthesis of four compound libraries based on scaffolds that have broad NP-like features, but that are only distantly related to specific NPs. The optimisation of syntheses of the scaffolds using [5 + 2] cycloaddition chemistry is detailed, together with methods to yield exemplar decorated screening compounds. In each case, a library was nominated for production, leading to a total of >2900 screening compounds that augmented the Joint European Compound Library of the European Lead Factory