TESTING OF ENERGY DISSIPATING CLADDING CONNECTIONS

Properly designed precast concrete cladding could potentially provide lateral stiffness, ductility, and energy dissipation for an overall building structure, especially during earthquakes. This paper describes a set of advanced connections that take advantage of the interaction between facade panels and structure (mainly due to horizontal interstorey drift) to dissipate energy, thereby reducing the response of the main structure. The results of an experimental program to characterize the hysteretic behaviour of advanced connections are presented. Design equations for the advanced connections are then calibrated against the test results, and the corresponding design charts are presented. It is anticipated that this research will lead to innovative ways of viewing the entire cladding system of a building.     

SEISMIC IMPACT LOADING IN INELASTIC TENSION-ONLY CONCENTRICALLY BRACED STEEL FRAMES: MYTH OR REALITY?

Tension-Only Concentrically Braced Frames (TOCBF) exhibit deteriorating pinched hysteretic behaviour during strong earthquakes. Slender braces transit between an elastic buckling state, a restraightening state, in which they carry almost no load, an elastic tensile loading state as they are suddenly taut and, finally, a tensile yielding state. It has long been suspected that the sudden increase in tensile forces in the braces of TOCBSF creates detrimental impact loading on the connections and other structural elements. No experimental evidence, however, has been provided so far to confirm, or to quantify, this impact phenomenon. This paper addresses this issue through shake table tests of half scale, two-storey, TOCBF models. By normalizing the hysteresis loops of braces obtained from shake table tests to the yield strength of steel obtained from quasi-static tests, the increase in tensile forces in the braces was obtained. Results of dynamic tensile tests on steel coupons under similar strain rates as observed during the shake table tests showed that this increase in tensile forces is not the result of impact, but is rather caused by a yield strength increase of the steel under high strain rate. A procedure is proposed to estimate and account for this increase in tensile forces in the braces at the design stage.     

Jeans Instability of a Protoplanetary Circular Disk Taking into Account the Magnetic Field and Radiation in Nonextensive Tsallis Kinetics

Solar System Research - Within the framework of Tsallis nonextensive statistics, the criteria for the Jeans gravitational instability are derived for a self-gravitating protoplanetary disk, whose...     

Resistance of Enzymes to Ionizing Radiation under Model Conditions of the Martian Regolith

Solar System Research - Ionizing radiation is one of the main factors that destroy biomolecules in extraterrestrial conditions. The effects of radiation depend on the conditions of the exposure...     

TERMO-LR Experiment on the Luna-27 Lander: Study of Thermophysical,Physicomechanical, and Electromagnetic Properties of the Lunar Soil

Solar System Research - The device is being developed for the TERMO-LR experiment on the Luna-27 lunar lander; it is intended for contact geophysical measurements of various properties of the lunar...     

On the Attractive Force of an Elliptical Gaussian Ring

Solar System Research - A numerical-analytical method for analyzing the orbital evolution of a planetary satellite under the influence of a perturbing body moving in an elliptical orbit is...     

Catalog of X-Ray Active Galactic Nuclei Based on ROSAT BSC and FSC Sources

Astrophysics - A general catalog of active galactic nuclei (AGN) has been created from identified optical sources of X-ray data from the Hamburg-ROSAT Catalog (HRC) and the Byurakan-Hamburg ROSAT...     

Constructing a Stäckel Model of the Galaxy: Solving the Problem of Whether the Vertical Density Distribution Is Realistic

Astronomy Letters - Techniques for solving the problem of constructing a Stäckel model by generalizing the potential from the equatorial plane to the entire space are considered. The initial...     

Determination of H II Region Metallicity in the Context of Estimating the Primordial Helium Abundance

Astronomy Letters - The primordial $${}^{4}$$ He abundance (Y $${}_{p}$$ ) is one of the key characteristics of Primordial Nucleosynthesis processes that occurred in the first minutes after the Big...     

Spectroscopic Redshift Measurements for Galaxy Clusters from the Lockman Hole Survey with the eROSITA Telescope Onboard the SRG Observatory

Astronomy Letters - We present the first results of our program of optical observations for galaxy clusters from the Lockman Hole X-ray survey with the eROSITA telescope onboard the SRG space...