Behaviour of functionally graded reinforced-concrete beams under cyclic loading

Tijekom zadnjih deset godina primjenjuje se slojevito mikroarmiranje kao nova metoda za proizvodnju armiranobetonskih elemenata. U radu su prikazani rezultati ispitivanja svojstava slojevito mikroarmiranih betonskih greda izloženih djelovanju cikličnog opterećenja. Za pripremu uzoraka primijenjena su čelična i polipropilenska vlakna. Betonske grede s potpunim kompozitnim djelovanjem ojačane su sa 0,5 do 2 % čeličnih vlakana, a slojevito mikroarmnirane grede sadrže 1,3 % čeličnih vlakana. Dobiveni rezultati pokazuju da se primjenom slojevitog mikroarmiranja betona povećava disipacija energije uslijed cikličkog opterećenjaOver the past decade, the functional grading has been applied as a new method for the manufacturing of reinforced-concrete elements. The objective of this investigation is to evaluate performance of the functionally graded reinforced-concrete beams exposed to cyclic loading. The steel and polypropylene fibres are used for the preparation of samples. Concrete beams with full composite action are strengthened with 0.5 to 2 % of steel fibres, and functionally graded RC beams contain 1.3 % of steel fibres. The use of the functionally graded method to reinforce concrete increases the dissipated energy due to the applied cyclic loading

Assessing influence of active and passive confinement on flexural behaviour of CFST beams

U radu se analizira utjecaj aktivnog i pasivnog ovijanja na ponašanje pri savijanju betonom ispunjenih čeličnih cijevi. Dvanaest ovijenih uzoraka podvrgnuto je ispitivanju čvrstoće na savijanje u tri točke. Osnovni varijabilni parametri bili su: odnos promjera i debljine cijevi (20, 30 i 60), tlačna čvrstoća betonske jezgre (15 MPa i 45 MPa) i vrsta ovijanja (aktivno ili pasivno). Ispitana je savojna čvrstoća, apsorpcija energije, fleksibilnost i način popuštanja ovijenih uzoraka, isto kao i način pucanja betonske jezgre u točki sloma. Rezultati pokazuju da aktivno ovijanje dovodi do manje duktilnosti uzoraka koji se odlikuju većom čvrstoćom betonske jezgre.The aim of this study is to investigate the effect of active and passive confinement on the flexural behaviour of concrete-filled steel tubes. Three-point flexural test is carried out on twelve confined specimens. The main variable parameters are: tube diameter to thickness ratio (20, 30, and 60), compressive strength of concrete core (15 MPa and 45 MPa), and type of confinement (active or passive). The flexural capacity, energy absorption, flexibility and failure mode of confined specimens, as well as the cracking pattern of concrete core at failure point, are evaluated in this study. The results show that active confinement leads to lower ductile behaviour in specimens with higher strength of concrete core

Evaluation of grooving method to postpone debonding of FRP laminates in WPC-FRP beams

The use of lightweight construction material with high corrosion resistance and low cost plays an important role in the design and construction of marine structures such as waterfronts. One of the most common methods for strengthening the structures is composite fibre reinforced plastic (FRP) sheet that is used for member retrofitting including wood plastic composite (WPC). The WPC material is produced from wood and compressed resin, which has good mechanical properties as well as economic benefits. The main problem of WPC reinforced with FRP sheets is the debonding of the sheet from WPC surface, which leads to premature and non-economic failure in members. One of the existing methods to solve this problem is surface preparation. However, surface preparation of wood plastic composite has some additional problems, such as operational cost, environmental pollution, etc. Therefore, to avoid debonding, another method has been used, known as the grooving method at the lower parts of beams. The laboratory used 50 I-shaped specimens with the same geometrical and mechanical properties. Initially, some slots such as longitudinal, transverse and diagonal grooves were created on the surface of specimens and filled by an epoxy. All beams were armed using one or two layers of GFRP sheets embedded at the lower part and were tested under four-point flexural loading. Grooves of different shapes, various widths and depths as well as the number of reinforcement layers were determined for considering their effect on the beam's behaviour. The results expressed that the debonding of FRP sheets can be delayed by selecting the longitudinal grooves with certain width and depth, which also leads to resistance improvement

The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

The accuracy of hydrodynamic force prediction for offshore structures and Morison's equation

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN005252 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Improving the seismic performance of eccentrically braced frames by using a ductile element

Stability of structures against earthquake is much important to prevent total or partial failure of structures and loss of financial and human investments of people and country. Eccentrically braced frames, as one of the most commonly used earthquake resistant systems, with good ductility and toughness, have different arrangements; one of them is Link beam-to-column connection. This type of connection was considered as bending form before the North Ridge earthquake (1994). But conducted research after the North Ridge Earthquake showed that the link beam-to-column connections were subjected to brittle failure, similar to connections which were located in Moment frames. So, after the North Ridge Earthquake, researchers began looking for ways to improve these types of connections, which indicates necessity of research in this field more than before. In this study, a new type of Energy absorption was introduced.  This absorption consists of a ring which increases the ductility and energy absorption of earthquake and a box to increase the bearing capacity which is connected to the ring through connection plates. for evaluating the performance of the proposed elements in steel frames with eccentrically braces, under nonlinear time history analysis, the OpenSees software has been used. The obtained Hysteresis curves suggest that introduced element can act as an energy absorbing member and a fuse to Reducing damage to structures with reduced rotation of link-beam, Cutting base and Relative story displacement in addition to providing the necessary ductility

Experimental study and calculation of confinement relationships for prestressed steel tube-confined compressed concrete stub columns

The current paper aims to present the results of an experimental investigation into the compressive strength of pre-stressed steel tube-confined compressed concrete (PSTC) stub columns. Here, to prestress the confined concrete, an innovative technique is utilized, in which the fresh concrete is subjected to compression while the steel tube is simultaneously preten-sioned laterally by applying external pressure to the fresh concrete. A total of 135 confined specimens were tested under axial compressive loading to determine the confinement strength of the specimens. Moreover, new confinement relationships for the load-carrying capacity of the PSTC columns were proposed in terms of the prestressing ratio ( r P ), reference concrete strength ( c f), and tube outer diameter to wall thickness ratio ( / Dt ). Finally, a parametric study was conducted to evaluate the effect that the parameters r P, c f , and / Dt have on the compressive strength of the prestressed confined concrete. The results indi-cate that the confined concrete prestressed by the present technique demonstrates significantly enhanced load-carrying capacity; however, increasing the prestressing level slightly affects it