Numerical investigation of tension reinforcement lap length of eurocode 2 using a four-point beam loading system

© 2019 Latin American Journal of Solids and Structures. All rights reserved. This report presents a computational research on Eurocode 2 (EC2) tension lap lengths (lo) design in a normally reinforced concrete beam, using ANSYS Workbench simulation software program by simulating a laboratory 4-point beam loading test system under static loading(discrete model approach). A typical 4-point laboratory setup loading system was modelled using an innovative and sustainable Finite Element Analysis (FEA) approach. In order to investigate the EC2 tension lap lengths (lo) design recommendation, a total of 100 analysis cases of lap lengths were considered for different reinforcement bar diameters of 10mm, 12mm, 16mm, 20mm and 25mm. The study has considered beam failure types, effects of failure load on the various lap length reduction cases and effects of steel reinforcement bar size changes on the design lap lengths. The analysis of results revealed that the yield strength of steel (fyk), diameter of tension reinforcement bar, (db), tensile strength of concrete (fctd) and concrete cover (cd) are the main parameters for a tension lap length design according to EC2. While a linear relationship exists between tension steel reinforcement bar sizes (db) and the obtained lap lengths (lo). The study reveals a potential use of 15% and 20% reduction in lap length (lo) for tension steel reinforcement bar sizes of 10mm, 16mm and 12mm and 20mm in comparison with the recommended design lap length of EC2. It was concluded that EC2 tension lap length design recommendation is conservative

Effect of Organic Matter on Swell and Undrained Shear Strength of Treated Soils

This paper presents a laboratory and statistical study on swell and undrained shear strength of cemented organic clays blended with eco-friendly (by-product) cementitious materials such as ground granulated blast slag (GGBS) and cement kiln dust (CKD). The presence of organic matter in soils can be very problematic especially during construction of infrastructures such as roads and foundations. Therefore, experimental and statistical investigations are crucial to further understand the effect of organic matter on swell and strength performance of soils treated with by-product materials (GGBS and CKD). Five artificially synthesised organic clays with 0%, 5%, 10%, 15% and 20% organic matters were mixed with 20% cement during the first phase of mixing. In the second phase, cement content was reduced to 4% and blended with 12% GGBS and 4% CKD respectively. All mixed samples were cured up to 56days and subjected to undrained triaxial test and one-dimensional oedometer swell test. The undrained shear strength of the untreated soils decreases from 22.47kPa to 15.6kPa upon increase in organic matter from 0-20%. While the swell increases from 1.17% to 3.83% for the same range of 0-20% organic matter. The results also show improvement on strength and swell upon addition of 20% cement for all investigated samples. For samples treated with 4% cement and inclusion of 12% GGBS and 4% CKD, the treated soils showed better performance in terms of swell potential due to reduction in plasticity compared to the plasticity of soils treated with 20% cement. Undrained shear strength increases from 632kPa to 804.9kPa and from 549.8kPa to 724.4kPa with reduction in organic matter upon addition of 20% CEM and 4% CEM: 12% GGBS: 4% CKD after 56days. The results obtained show that the inclusion of GGBS and CKD reduced swell and increases undrained shear strength irrespective of the percentage of organic materials due to cementation effect. However, results of the statistical studies show that the presence of organic matter influences the extent of performance of the cement, GGBS and CKD treated soils. <br/

Thermal Performance of Radiant Floor Heating Systems Concrete Slabs with Embedded Fine Steel

This paper investigated the application of recycled steel powder as an additive in concrete to increase the thermal properties of radiant floor heating systems (RFHS). The project aimed to increase the efficiencies of thermal conductivities, allowing radiant heat to produce higher energy efficient outputs for heating. Thermocouple readings measured lower temperatures with similar heating conditions as a standard mix slab due to heat transfer occurring evenly through a large surface area, thus transferring heat to the air at faster rates. The tests were completed by casting two 400×400×200mm deep slabs enclosing radiant heating pipes. Water was pumped at 40 and 60oC through the pipes. The temperature was recorded at various positions throughout the slab that would allow the multi-layered cylinder approach to analyse the rate of heat transfer, and calculate the efficiency of the heat transfer. The crushing strength of the proposed mix using steel powder replacement is shown to be reduced by 26% when a mix with 12.4% of steel powder is used. Contrary to the original hypothesis of this research, the investigation found rates of heat transfer during the heating stage were 3% lower for the mix containing steel powder compared to the standard mix

Effects of waste plastics as partial fine-aggregate replacement for reinforced low-carbon concrete pavements

Using waste plastics as a partial natural aggregate replacement and monitoring strength and workability reduction in pavement structures is vital to net-carbon zero. This study explores the utilisation of waste plastic as a fine aggregate replacement in medium-strength reinforced concrete pavements, for improving plastic aggregate performance and the intrinsic reasoning for observed strength performance. Various weight fractions of fines were substituted by the same weight of plastic aggregates ranging from 5–15% according to the appropriate standards (Eurocodes and British Standards). The physical and mechanical properties of the composites were analysed. The results indicated that the use of polymeric materials as a partial replacement for fines contributed to a decrease in workability, compressive strength and push-out bond between steel reinforcement and concrete. Despite these trends, 5% replacement of fine aggregates with plastic waste surpassed all the feasibility criteria. Furthermore, using 10% of plastic replacement by weight was deemed feasible in non-structural applications such as roads, pavements, and facades. The outputs have demonstrated environmental engineering concepts in tackling plastic waste, providing an alternative to conventional aggregate. Environmental benefits can arise due to the removal of potentially hazardous plastics from entering ecosystems as well as minimising dredging of global sand reserves

Additional file 1 of Trend and disparities in authorship of healthcare-related publications on the ongoing Russia-Ukraine war

Supplementary Material