Stiffness of Concrete-Filled Steel Deck Diaphragms

In structural analysis of building structures, the in-plane stiffness diaphragms is needed so that lateral loads will be properly distributed to elements of the lateral-force resisting system. In US building codes, diaphragm stiffness is used to determine whether a diaphragm can be assumed rigid or flexible and is also used in semi-rigid diaphragm analysis. For concrete-filled steel deck diaphragms, methods provided in AISI S310 (AISI, 2020) to calculate stiffness have relied on empirical formulas while past research by Porter and Easterling (1988) suggests that mechanical models and theoretical formulas can accurately capture stiffness. Recently, eight cantilever diaphragm specimens were tested with variations in depth of concrete cover, deck depth, perimeter stud anchor configuration, concrete type (normal weight (NW) and lightweight (LW)), and the presence of either welded wire mesh or reinforcing steel. This report summarizes the results of this testing program as they relate to initial stiffness. The initial stiffness results of this testing program are used in conjunction with the results of a testing program performed Porter and Easterling (1988) to form a set of 25 specimens that are then used to validate a proposed prediction model for the initial stiffness of concrete-filled steel deck diaphragms. The proposed prediction model is based on a theoretical framework proposed by Porter and Easterling (1988) which concluded that the initial stiffness of a concrete-filled steel deck diaphragm is a combination of 1) the diaphragm shear stiffness, 2) the bending stiffness of the concrete-filled steel deck diaphragm combined with the chords, and 3) the stiffness of the shear transfer connections between the concrete-filled steel deck diaphragm and the supporting steel frame. The proposed stiffness predictions using this approach resulted in an average ratio of predicted stiffness to measured stiffness equal to 0.95 with a standard deviation of 0.21. Based on this comparison for 25 cantilever diaphragm specimens, it was deemed that the prediction model accurately represents the initial shear stiffness of concrete-filled steel deck diaphragms. This report also includes two examples to illustrate of how the proposed prediction model can be used to calculate diaphragm deflections for two different diaphragm configurations. The results of these examples showed that for the cantilever diaphragm configuration, the deflection of the free end is mostly due to the shear deformation of the concrete-filled steel deck diaphragm or to the deformation of the shear transfer connection, depending on the spacing of headed stud anchors, with the bending deformations contributing the least to the total deflection. For the case of a simply supported diaphragm, the mid-span deflection was attributed primarily to bending deformations of the diaphragm (78% of total deflection), with shear deformations contributing to approximately 25% of the total deflection and the deformation of the shear transfer connections contributing less than 1% of the total deflection.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

Low- And medium-spin negative-parity bands in the Os 187 nucleus

Low- and medium-spin negative-parity bands of Os187 have been studied using the AFRican Omnipurpose Detector for Innovative Techniques and Experiments (AFRODITE) array, following the W186(He4,3n)Os187 reaction at a beam energy of 37 MeV. In the current work, all the previously known bands have been significantly extended and three new bands have been added to the level scheme. The angular distribution ratio (RAD) and polarization measurements have been used to assign spin and parity to the observed new levels. The configurations of some of the bands have been modified. The observed bands are interpreted within the cranked shell model (CSM) and cranked Nilsson-Strutinsky-Bogoliubov (CNSB) formalism. Comparison with experimental data shows good agreements. Systematic comparison with the neighboring Os185 isotope is also discussed

Spectral fluctuation properties of spherical nuclei

The spectral fluctuation properties of spherical nuclei are considered by use of NNSD statistic. With employing a generalized Brody distribution included Poisson, GOE and GUE limits and also MLE technique, the chaoticity parameters are estimated for sequences prepared by all the available empirical data. The ML-based estimated values and also KLD measures propose a non regular dynamic. Also, spherical odd-mass nuclei in the mass region, exhibit a slight deviation to the GUE spectral statistics rather than the GOE.Comment: 10 pages, 2 figure

SDII Building Archetype Design v2.0

Building designs, SAP models, spreadsheets, and slide decks in support of SDII building archetype designs.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, Rs=2 for steel deck with fill and 2.5 for bare steel deck, and Rs=3 in designs. Inform areas for needed experimentation, and create targets for advancing nonlinear analysis within the full SDII effort.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

Comment on ``Evidence Against Instanton Dominance of Topological Charge Fluctuations in QCD''

We comment on the recent paper (hep-lat/0102003) by Horvath, Isgur, McCune, and Thacker, which concludes that the local chiral structure of fermionic eigenmodes is not consistent with instanton dominance. Our calculations, done with an overlap action, suggest the opposite conclusion.Comment: 5 pages, Revtex, 4 postscript figures. COLO-HEP-45

Cantilever Testing of Concrete-Filled Steel Deck Composite Diaphragms Using Various Types of Steel Reinforcing

This report provides a summary of nonlinear response history analyses conducted on a three- dimensional model of a series of steel buildings with special concentric braced frames (SCBFs). The models are conducted in OpenSees and include appropriate nonlinear response for the braced frames as well as the concrete-filled steel deck diaphragms and bare steel deck roofs. Additionally the buildings are designed considering traditional diaphragm design as defined by ASCE 7-16 12.10.1 as well as the new alternative diaphragm design procedures of ASCE 7-16 12.10.3. These alternative procedures have a seismic response modification coefficient, Rs, which is specific to the diaphragm system. Rs values between 1 and 3 are investigated herein. The results indicate that SCBF building performance is sensitive to the diaphragm design, and that traditional diaphragm design does not lead to acceptable levels of performance. Use of the alternative diaphragm design procedure with Rs=2.0 for concrete-filled steel deck floors and Rs=2.5 for bare steel deck roofs is recommended. Future work is needed to continue to refine collapse criteria for 3D building models and to allow the engineer greater clarity in the extent of expected inelasticity in the vertical system vs. the diaphragm system when different combinations of R and Rs, i.e. different combinations of vertical and horizontal lateral force resisting systems, are employed.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

Calibration of Tethered Particle Motion Experiments

The Tethered Particle Motion (TPM) method has been used to observe and characterize a variety of protein-DNA interactions including DNA loping and transcription. TPM experiments exploit the Brownian motion of a DNA-tethered bead to probe biologically relevant conformational changes of the tether. In these experiments, a change in the extent of the bead’s random motion is used as a reporter of the underlying macromolecular dynamics and is often deemed sufficient for TPM analysis. However, a complete understanding of how the motion depends on the physical properties of the tethered particle complex would permit more quantitative and accurate evaluation of TPM data. For instance, such understanding can help extract details about a looped complex geometry (or multiple coexisting geometries) from TPM data. To better characterize the measurement capabilities of TPM experiments involving DNA tethers, we have carried out a detailed calibration of TPM magnitude as a function of DNA length and particle size. We also explore how experimental parameters such as acquisition time and exposure time affect the apparent motion of the tethered particle. We vary the DNA length from 200 bp to 2.6 kbp and consider particle diameters of 200, 490 and 970 nm. We also present a systematic comparison between measured particle excursions and theoretical expectations, which helps clarify both the experiments and models of DNA conformation

Spin-one color superconductivity in compact stars?- an analysis within NJL-type models

We present results of a microscopic calculation using NJL-type model of possible spin-one pairings in two flavor quark matter for applications in compact star phenomenology. We focus on the color-spin locking phase (CSL) in which all quarks pair in a symmetric way, in which color and spin states are locked. The CSL condensate is particularly interesting for compact star applications since it is flavor symmetric and could easily satisfy charge neutrality. Moreover, the fact that in this phase all quarks are gapped might help to suppress the direct Urca process, consistent with cooling models. The order of magnitude of these small gaps (~1 MeV) will not influence the EoS, but their also small critical temperatures (T_c ~800 keV) could be relevant in the late stages neutron star evolution, when the temperature falls below this value and a CSL quark core could form.Comment: 7 pages, 7 figures, revised version, accepted for the Conference Proceedings of "Isolated Neutron Stars: from the Interior to the Surface", London, 24-28. April 200

The Seven-sphere and its Kac-Moody Algebra

We investigate the seven-sphere as a group-like manifold and its extension to a Kac-Moody-like algebra. Covariance properties and tensorial composition of spinors under $S^7$ are defined. The relation to Malcev algebras is established. The consequences for octonionic projective spaces are examined. Current algebras are formulated and their anomalies are derived, and shown to be unique (even regarding numerical coefficients) up to redefinitions of the currents. Nilpotency of the BRST operator is consistent with one particular expression in the class of (field-dependent) anomalies. A Sugawara construction is given.Comment: 22 pages. Macropackages used: phyzzx, epsf. Three epsf figure files appende

The effect of ozone on progression or regression of artificial caries-like enamel lesions in vitro

Objective: This study investigated the effect of ozone on the progression or regression of artificial caries-like lesions on enamel following pH cycling conditions in vitro. Methods: A randomized, single blind, four legs design was used. 20 full thickness enamel slabs were allocated to each of the four groups which were: Fluoride free toothpaste (control); ozone alone; Reductant/Patient Kit alone and a combination of both ozone/Reductant/Patient Kit. Artificial lesions were created and subjected to the pH cycling regime for a 14 days period. Assessments were carried out before and after the pH cycling on the slabs using the microhardness testing and Quantitative Light-induced Fluorescence (QLF). Results: Statistical significant difference were found in the percentage change of enamel microhardness before and after pH cycling between ozone/Reductant/Patient Kit group and all the other three groups of the study, as well as between Reductant/Patient Kit group and control. There was a statistical significant difference in the change of size and severity of the lesion (ΔQ) between all the three regimes tested and the control with a trend favouring ozone/Reductant/Patient Kit group. Conclusions: In our model, it appeared that ozone treatment alone is not effective in protecting the enamel against demineralisation or promoting remineralisation, unless combined with the Reductant/Patient Kit, which contain high levels of fluoride