The effect of the number of response cycles on the behaviour of reinforced concrete elements subject to cyclic loading

The development of damage in reinforced concrete (RC) structures is a cumulative process. Some damage indices used to quantify damage make use of the number of response cycles as an Engineering Demand Parameter (EDP) relating with damage development. Other indices make use of deformation in terms of displacement or chord rotation. These functions are generally a function of whether the response is monotonic or cyclic, and are insensitive to the number of major deflection cycles leading to that state of damage. Many such relations are derived from experimental data from low-cycle fatigue tests performed on RC elements. The loading in such tests generally consists of either a monotonic increase in load or a gradually increasing cyclic load. Since damage development is a cumulative process, and hence depends on the load history, the loading pattern in low-cycle fatigue tests for assessment purposes should reflect the response of an earthquake. This paper will discuss a procedure to determine a loading history for cyclic tests, based on earthquake demands. The preliminary results of a campaign of low-cycle fatigue tests on RC elements to investigate the effect of using different load histories are also discussed

Low cycle fatigue tests of reinforced concrete columns and joints built with ribbed reinforcement and plain stirrups

The majority of existing reinforced concrete (RC) buildings were built prior to the introduction of seismic codes. As observed in various recent earthquakes, due to their lack of structural capacity and ductility such structures are very vulnerable and have suffered considerable damage. The number of cyclic tests that have been carried out to investigate the behaviour of RC components with detailing typical of these buildings is very limited. Such tests are very relevant for seismic vulnerability assessment purposes. In this paper, a low-cycle fatigue testing campaign on RC columns and connections specifically devised to investigate various physical parameters that affect damage development, is presented. The campaign consists of 19 columns and 7 beam-column connections. Some of the preliminary results and observations are presented and discussed

Lysine Supplementation of Barley-Soybean Meal Diets for Growing Pigs

The lysine requirement of pigs as suggested by the National Research Council (NRC) was determined using corn-soybean meal based diets. More recent research has indicated that differences exist in the availability of lysine in different ingredients. It has been suggested that lysine in barley is less available than lysine in corn. Thus, it is possible that diets formulated with barley and soybean meal to meet the NRC\u27s suggested lysine requirement, might actually be deficient in this amino acid. This study was conducted to determine the lysine needs of pigs fed barley-soybean meal diets from approximately 45 to 75 lb

VLA Observations of the Infrared Dark Cloud G19.30+0.07

We present Very Large Array observations of ammonia (NH3) (1,1), (2,2), and CCS (2_1-1_0) emission toward the Infrared Dark Cloud (IRDC) G19.30+0.07 at ~22GHz. The NH3 emission closely follows the 8 micron extinction. The NH3 (1,1) and (2,2) lines provide diagnostics of the temperature and density structure within the IRDC, with typical rotation temperatures of ~10 to 20K and NH3 column densities of ~10^15 cm^-2. The estimated total mass of G19.30+0.07 is ~1130 Msun. The cloud comprises four compact NH3 clumps of mass ~30 to 160 Msun. Two coincide with 24 micron emission, indicating heating by protostars, and show evidence of outflow in the NH3 emission. We report a water maser associated with a third clump; the fourth clump is apparently starless. A non-detection of 8.4GHz emission suggests that the IRDC contains no bright HII regions, and places a limit on the spectral type of an embedded ZAMS star to early-B or later. From the NH3 emission we find G19.30+0.07 is composed of three distinct velocity components, or "subclouds." One velocity component contains the two 24 micron sources and the starless clump, another contains the clump with the water maser, while the third velocity component is diffuse, with no significant high-density peaks. The spatial distribution of NH3 and CCS emission from G19.30+0.07 is highly anti-correlated, with the NH3 predominantly in the high-density clumps, and the CCS tracing lower-density envelopes around those clumps. This spatial distribution is consistent with theories of evolution for chemically young low-mass cores, in which CCS has not yet been processed to other species and/or depleted in high-density regions.Comment: 29 pages, 9 figures, accepted for publication by ApJ. Please contact the authors for higher resolution versions of the figure

Mean first passage time analysis reveals rate-limiting steps, parallel pathways and dead ends in a simple model of protein folding

We have analyzed dynamics on the complex free energy landscape of protein folding in the FOLD-X model, by calculating for each state of the system the mean first passage time to the folded state. The resulting kinetic map of the folding process shows that it proceeds in jumps between well-defined, local free energy minima. Closer analysis of the different local minima allows us to reveal secondary, parallel pathways as well as dead ends.Comment: 7 page

What thermodynamic features characterize good and bad folders? Results from a simplified off-lattice protein model

The thermodynamics of the small SH3 protein domain is studied by means of a simplified model where each bead-like amino acid interacts with the others through a contact potential controlled by a 20x20 random matrix. Good folding sequences, characterized by a low native energy, display three main thermodynamical phases, namely a coil-like phase, an unfolded globule and a folded phase (plus other two phases, namely frozen and random coil, populated only at extremes temperatures). Interestingly, the unfolded globule has some regions already structured. Poorly designed sequences, on the other hand, display a wide transition from the random coil to a frozen state. The comparison with the analytic theory of heteropolymers is discussed

Barley Diets for Growing-Finishing Pigs

Barley is an important feed ingredient that may be used as an alternative for corn in swine diets. It is higher in protein and the amino acid lysine than is corn. But, it also contains less energy than corn and thus diets based on barley as the grain source are less efficient than corn based diets. It has also been suggested that hogs fed barley diets do not yield ~s well as those fed corn diets. The objectives of this experiment were to determine the effect of lysine and fat supplementation to barley based diets and to compare these diets with corn based diets. A further objective was to determine the effect of barley diets on carcass characteristics and dressing percentage

Effect of Tryptophan Supplementation of a Low Protein, Corn-Sunflower Meal Diet for Young Growing Pigs

Research conducted at South Dakota State University and reported in the 1983 and 1984 Swine Field Day Proceedings, indicated that the amino acid tryptophan is limiting in a lysine supplemented, 12% protein, corn-sunflower meal diet fed to young weaned pigs. This trial was conducted to further study the effects of tryptophan supplementation of an amino acid fortified, 12% protein, corn-sunflower meal diet and to estimate the dietary tryptophan requirement of the young weaned pig fed that diet

Effect of Added Threonine in a Lysine Supplemented, Low Protein Corn-Sunflower Meal Diet

Threonine has been shown to be one of the limiting amino acids in certain types of swine diets. Recent research indicates that the level of threonine required by the young growing pig may be greater than that suggested by the National Research Council (NRC). Research reported in the 1983 Swine Field Day Proceedings, indicated that lysine, threonine and tryptophan are the first three limiting amino acids in a corn-sunflower meal diet with lysine being most deficient. The trial reported, herein, was conducted to identify the optimum level of threonine required by the young growing pig fed a low protein, lysine supplemented corn-sunflower meal diet

Effect of Added tryptophan in a Lysine Supplemented Low-Protein, Corn-Soybean Meal Diet

South Dakota\u27s production of sunflowers has been increasing during recent years and sunflowers are now recognized as an important crop in the state. Sunflowers are an excellent source of oil, with certain varieties containing up to 40% oil. Similar to soybean meal, the by-product of sunflower oil processing is a meal which can be used as a source of protein in formulating swine rations. A previous experiment, reported in the 1983 Swine Field Day Proceedings, indicated that the limiting amino acids in a corn-sunflower meal diet are lysine, tryptophan and threonine. This study was conducted to identify the optimum level of tryptophan in a lysine fortified low-protein, corn-sunflower meal diet for young growing pigs