Deformations in deep continuous reinforced concrete transfer girders

peer reviewedThis paper presents a three-parameter kinematic model for the deformation patterns of deep continuous transfer girders. The three degrees of freedom of the model are the average strains along the top and bottom longitudinal reinforcements within each shear span, as well as the transverse displacement in the critical loading zone. The model is validated with the help of a large test of a two-span continuous beam performed at the University of Toronto. It is shown that the apparently complex deformation patterns of the specimen are captured well by the kinematic model

pySEOBNR: a software package for the next generation of effective-one-body multipolar waveform models

We present pySEOBNR, a Python package for gravitational-wave (GW) modeling developed within the effective-one-body (EOB) formalism. The package contains an extensive framework to generate state-of-the-art inspiral-merger-ringdown waveform models for compact-object binaries composed of black holes and neutron stars. We document and demonstrate how to use the built-in quasi-circular precessing-spin model SEOBNRv5PHM, whose aligned-spin limit (SEOBNRv5HM) has been calibrated to numerical-relativity simulations and the nonspinning sector to gravitational self-force data using pySEOBNR. Furthermore, pySEOBNR contains the infrastructure necessary to construct, calibrate, test, and profile new waveform models in the EOB approach. The efficiency and flexibility of pySEOBNR will be crucial to overcome the data-analysis challenges posed by upcoming and next-generation GW detectors on the ground and in space, which will afford the possibility to observe all compact-object binaries in our Universe.Comment: 21 pages, 4 figure

Laying the foundation of the effective-one-body waveform models SEOBNRv5: improved accuracy and efficiency for spinning non-precessing binary black holes

We present SEOBNRv5HM, a more accurate and faster inspiral-merger-ringdown gravitational waveform model for quasi-circular, spinning, nonprecessing binary black holes within the effective-one-body (EOB) formalism. Compared to its predecessor, SEOBNRv4HM, the waveform model i) incorporates recent high-order post- Newtonian results in the inspiral, with improved resummations, ii) includes the gravitational modes (l, |m|) = (3, 2), (4, 3), in addition to the (2, 2), (3, 3), (2, 1), (4, 4), (5, 5) modes already implemented in SEOBNRv4HM, iii) is calibrated to larger mass-ratios and spins using a catalog of 442 numerical-relativity (NR) simulations and 13 additional waveforms from black-hole perturbation theory, iv) incorporates information from second-order gravitational self-force (2GSF) in the nonspinning modes and radiation-reaction force. Computing the unfaithfulness against NR simulations, we find that for the dominant (2, 2) mode the maximum unfaithfulness in the total mass range $10-300 M_{\odot}$ is below $10^{-3}$ for 90% of the cases (38% for SEOBNRv4HM). When including all modes up to l = 5 we find 98% (49%) of the cases with unfaithfulness below $10^{-2} (10^{-3})$, while these numbers reduce to 88% (5%) when using SEOBNRv4HM. Furthermore, the model shows improved agreement with NR in other dynamical quantities (e.g., the angular momentum flux and binding energy), providing a powerful check of its physical robustness. We implemented the waveform model in a high-performance Python package (pySEOBNR), which leads to evaluation times faster than SEOBNRv4HM by a factor 10 to 50, depending on the configuration, and provides the flexibility to easily include spin-precession and eccentric effects, thus making it the starting point for a new generation of EOBNR waveform models (SEOBNRv5) to be employed for upcoming observing runs of the LIGO-Virgo-KAGRA detectors

Geminin Is Required for Zygotic Gene Expression at the Xenopus Mid-Blastula Transition

In many organisms early development is under control of the maternal genome and zygotic gene expression is delayed until the mid-blastula transition (MBT). As zygotic transcription initiates, cell cycle checkpoints become activated and the tempo of cell division slows. The mechanisms that activate zygotic transcription at the MBT are incompletely understood, but they are of interest because they may resemble mechanisms that cause stem cells to stop dividing and terminally differentiate. The unstable regulatory protein Geminin is thought to coordinate cell division with cell differentiation. Geminin is a bi-functional protein. It prevents a second round of DNA replication during S and G2 phase by binding and inhibiting the essential replication factor Cdt1. Geminin also binds and inhibits a number of transcription factors and chromatin remodeling proteins and is thought to keep dividing cells in an undifferentiated state. We previously found that the cells of Geminin-deficient Xenopus embryos arrest in G2 phase just after the MBT then disintegrate at the onset of gastrulation. Here we report that they also fail to express most zygotic genes. The gene expression defect is cell-autonomous and is reproduced by over-expressing Cdt1 or by incubating the embryos in hydroxyurea. Geminin deficient and hydroxyurea-treated blastomeres accumulate DNA damage in the form of double stranded breaks. Bypassing the Chk1 pathway overcomes the cell cycle arrest caused by Geminin depletion but does not restore zygotic gene expression. In fact, bypassing the Chk1 pathway by itself induces double stranded breaks and abolishes zygotic transcription. We did not find evidence that Geminin has a replication-independent effect on transcription. We conclude that Geminin is required to maintain genome integrity during the rapid cleavage divisions, and that DNA damage disrupts zygotic gene transcription at the MBT, probably through activation of DNA damage checkpoint pathways

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

A Two Degree of Freedom Kinematic Model for Predicting the Deformations of Deep Beams

peer reviewedIn modern construction, it is not unusual to require a short span member to carry a very large load such as with a transfer girder. These members generally have high shear strengths with strut-and-tie models being able to predict these strengths generally in a conservative manner. For serviceability checks, cracked stiffness estimates, and seismic design, however, it is also important to be able to predict the deformations of the member accurately. In this paper a set of eight large and heavily instrumented reinforced concrete deep beams subjected to monotonic or cyclic loading are summarized. The displacements of these tests are explained in detail with particular attention paid to the development of deformations over the full load history. From these deformations, the paper notes that a simple 2 degree of freedom (DOF) kinematic model can be developed to predict the entire displacement field for a beam after diagonal cracking has occurred. These two degrees of freedom are the average longitudinal strain in the flexural reinforcement, and the vertical distortion of the critical loading zone near the applied load. When the results of the measured displacements of the beam tests are compared to the pattern of deformations from the 2 DOF model, excellent agreement is obtained. In addition, it is shown that the width of the main diagonal crack can also be explained well using the same 2 DOF model once these parameters are known. A forthcoming paper will explain how these parameters themselves can be predicted

Behavior of Deep Beams with Large Headed Bars

peer reviewedWhile anchor heads are particularly useful in the case of large bars which require significant development lengths, the ACI code provides design guidance for bars #11 or smaller. This paper presents a test of a large deep beam reinforced with a single #18 headed bar. The behavior of the beam is evaluated in comparison to the behavior of a specimen with more conventional reinforcement of 6#8 headed bars, and to the behavior of a specimen with lap-spliced anchor hooks. Despite the extreme detailing of the specimen with a single #18 bar, the beam had the same strength as the specimen with 6#8 bars. The compressive stress in front of the anchor head reached about 1.5 times the compressive strength of the concrete and the stress in the #18 bar reached about 414 MPa (60 ksi) before the beam failed in shear along a diagonal crack away from the anchorage zone. Shear strength calculations according to Appendix A of the ACI code showed that the current strut-and-tie provisions can overestimate the shear strength of deep beams by as much as 23%

Behavior of Large Deep Beams Subjected to Monotonic and Reversed Cyclic Shear

An experimental study on eight large reinforced concrete deep beams was performed. The variables were the shear-span-to-depth ratio (a/d = 1.55 or 2.29), quantity of stirrups (0.0 or 0.1%) and type of loading (monotonic or fully reversed cyclic). All members failed in shear before yielding of the longitudinal reinforcement. The provision of only 0.1% of transverse reinforcement significantly decreased crack widths at service load levels and significantly increased the shear strength. For members with stirrups, the load-deformation response measured under monotonic loading provided an excellent envelope to the cyclic response and the shear strength under reversed cyclic loading was not significantly reduced. For the members without stirrups, somewhat surprisingly, those tested under reversed cyclic loading failed at significantly higher shear forces than their companion monotonically loaded specimens