Mechanical behaviour of PVC-CFRP confined concrete column with RC beam joint subjected to axial load

U radu je prikazano eksperimentalno istraživanje oblika loma, granične čvrstoće, deformacija i krivulja opterećenje-pomak spoja betonskog stupa obavijenog PVC-CFRP-om i AB grede (PCRBJ) za slučaj osnog opterećenja. Uzorci spoja betonskog stupa obavijenog PVC-om i AB grede (PRBJ) i devet uzoraka PCRBJ projektirani su prema načelu slabog stupa i čvrstog spoja. Predložen je pristup numeričke analize za prikladno predviđanje krivulje opterećenje – pomak. Utvrđeno je da se numerički predviđene vrijednosti dobro podudaraju s rezultatima ispitivanja.An experimental investigation on failure mode, ultimate strength, strain variation, and load-displacement curves of PVC-CFRP confined concrete column with reinforced concrete (RC) beam joint (PCRBJ) subjected to axial load was conducted in this study. Samples of a PVC confined concrete column with RC beam joint (PRBJ) and nine PCRBJs were designed using the principle of weak column and strong joint. A numerical analysis approach for convenient prediction of the load-displacement curve of specimen was proposed. It was established that the estimated values are in good agreement with test data

Mantle Flow Underneath the South China Sea Revealed by Seismic Anisotropy

It Has Long Been Established that Plastic Flow in the Asthenosphere Interacts Constantly with the overlying Lithosphere and Plays a Pivotal Role in Controlling the Occurrence of Geohazards Such as Earthquakes and Volcanic Eruptions. Unfortunately, Accurately Characterizing the Direction and Lateral Extents of the Mantle Flow Field is Notoriously Difficult, Especially in Oceanic Areas Where Deployment of Ocean Bottom Seismometers (OBSs) is Expensive and Thus Rare. in This Study, by Applying Shear Wave Splitting Analyses to a Dataset Recorded by an OBS Array that We Deployed between Mid-2019 and Mid-2020 in the South China Sea (SCS), We Show that the Dominant Mantle Flow Field Has a NNW-SSE Orientation, Which Can Be Attributed to Mantle Flow Extruded from the Tibetan Plateau by the Ongoing Indian-Eurasian Collision. in Addition, the Results Suggest that E-W Oriented Flow Fields Observed in South China and the Indochina Peninsula Do Not Extend to the Central SCS

The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra

This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17)

The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra

This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17)

The 16th Data Release of the Sloan Digital Sky Surveys : First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra

This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).Peer reviewe

The Seventeenth Data Release of the Sloan Digital Sky Surveys: Complete Release of MaNGA, MaStar and APOGEE-2 Data

This paper documents the seventeenth data release (DR17) from the Sloan Digital Sky Surveys; the fifth and final release from the fourth phase (SDSS-IV). DR17 contains the complete release of the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which reached its goal of surveying over 10,000 nearby galaxies. The complete release of the MaNGA Stellar Library (MaStar) accompanies this data, providing observations of almost 30,000 stars through the MaNGA instrument during bright time. DR17 also contains the complete release of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) survey which publicly releases infra-red spectra of over 650,000 stars. The main sample from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), as well as the sub-survey Time Domain Spectroscopic Survey (TDSS) data were fully released in DR16. New single-fiber optical spectroscopy released in DR17 is from the SPectroscipic IDentification of ERosita Survey (SPIDERS) sub-survey and the eBOSS-RM program. Along with the primary data sets, DR17 includes 25 new or updated Value Added Catalogs (VACs). This paper concludes the release of SDSS-IV survey data. SDSS continues into its fifth phase with observations already underway for the Milky Way Mapper (MWM), Local Volume Mapper (LVM) and Black Hole Mapper (BHM) surveys

Degradation Behavior of the Preload Force of High-Strength Bolts after Corrosion

Corrosion significantly affects the structural behavior of members in a connection (i.e., the thickness of steel plates, the preload force of bolts, and the friction factor of steel plates). Safety assessment of corroded steel frames (i.e., beam-to-column connection, beams, or columns) has been a major concern in engineering. In this work, an experiment of accelerated corrosion testing is carried out to obtain corroded specimens connected with high-strength bolts, and the preload force of high-strength bolts (PF-HSB) is monitored throughout the whole stage of the corrosion testing. Before the corrosion testing, the PF-HSB caused by the stress relaxation is also recorded. The PF-HSB decreases rapidly in the first five hours after the final screwing of bolts and it keeps stable after 100 h. The PF-HSB is seriously affected by corrosion, which decreases by 30.0% of the original preload force when the corrosion rate of steel plate reaches 3.5%. A finite element method for predicting the PF-HSB after corrosion is proposed. An estimation model for the PF-HSB considering the stress relaxation is established. A degradation model for predicting the PF-HSB after corrosion is also suggested, and is in good agreement with experimental data. The results of this research are of great significance for the safety assessment of in-service steel structures

Measurement and analysis of the radial motion error of aerostatic ultra-precision spindle

The measurement of the rotation error of an aerostatic ultra-precision spindle is critically important to evaluate and hence ensure the precision of machine tools. The Donaldson reversal method, which was taken as the efficient method for error separation theoretically, has been widely used to separate shape errors of standard artifact. However, the accuracy analysis of the Donaldson reversal method has not been fully studied and understood. In this study, a nanometer system for measuring the radial rotation error of aerostatic ultra-precision spindle was constructed based on the Donaldson reversal method. The comparative experiments were carried out to investigate the effects of the motor drive, and an angle correction algorithm was proposed to alleviate the effect of angle deviation. The method of harmonic analysis was applied to investigate the effect of artifact eccentricity, and the relationship between the axial motion and measuring error was also studied. The measuring accuracy can be improved by reducing the cogging torque of motor, the angle deviation, artifact eccentricity and spindle axial motion. Experimental results showed that the measurement uncertainty of both the spindle rotation error and artifact form error can be controlled in nanometer level. Besides, the separated value of the artifact form error was very close to the nominal roundness, which verifies the accuracy of the measurement system and the validity of the error separation method

Hysteresis performance of steel beam-column welded T-joints corroded in steel industrial atmosphere

This study investigates the effect of steel industrial corrosion on the seismic behavior of beam-column welded T-joints. An environmental and corrosion state survey in a sintering plant reveals high temperatures (up to 45 °C), high humidity (up to 58 %), and a high concentration of corrosive gases, particularly SO2 (average 1.3 mg/m3, peak 5.4 mg/m3), contributing to extensive structural damage. Based on the measured environmental conditions, an accelerated corrosion test method is developed to replicate the full-scale corroded beam-column welded T-joints. The corrosion characteristics analysis indicates that the corrosion severity varies across different parts, with the lower flange of the beam experiencing the most corrosion, followed by the upper flange and web. Subsequently, hysteresis performance tests on five corroded T-joints examines the effect of steel industrial corrosion on their seismic performance, including the failure modes, hysteresis curves and skeleton curves, bearing and deformation capability, stiffness and energy dissipation. The results indicated that corrosion in T-joint specimens results in a linear decrease in loads and displacements at yield and peak points, accompanied by a significant reduction in stiffness and failure cycles. Corrosion impacts the ductility and energy dissipation of T-joints more than load-bearing capacity, affecting seismic performance more severely. Although corrosion allowance ensures the residual load bearing capacity, it's not cost-effective in mitigating the effect of corrosion on seismic performance of beam-column welded T-joints