Experimental and numerical investigation of a method for strengthening cold-formed steel profiles in bending

Perforated cold-formed steel (CFS) beams subjected to different bending scenarios should be able to deal with different buckling modes. There is almost no simple way to address this significant concern. This paper investigates the bending capacity and flexural behavior of a novel-designed system using bolt and nut reinforcing system through both experimental and numerical approaches. For the experiential program, a total of eighteen specimens of three types were manufactured: a non-reinforced section, and two sections reinforced along the upright length at 200 mm and 300 mm pitches. Then, monotonic loading was applied to both the minor and major axes of the specimens. The finite element models were also generated and proved the accuracy of the test results. Using the proposed reinforcing system the flexural capacity of the upright sections was improved around either the major axis or minor axis. The 200 mm reinforcement type provided the best performance of the three types. The proposed reinforcing pattern enhanced flexural behavior and constrained irregular buckling and deformation. Thus, the proposed reinforcements can be a very useful and cost-effective method for strengthening all open CFS sections under flexural loading, considering the trade-off between flexural performance and the cost of using the method

Experimental and numerical investigation of a method for strengthening cold-formed steel profiles in bending

© 2020 by the authors. Perforated cold-formed steel (CFS) beams subjected to different bending scenarios should be able to deal with different buckling modes. There is almost no simple way to address this significant concern. This paper investigates the bending capacity and flexural behavior of a noveldesigned system using bolt and nut reinforcing system through both experimental and numerical approaches. For the experiential program, a total of eighteen specimens of three types were manufactured: a non-reinforced section, and two sections reinforced along the upright length at 200 mm and 300 mm pitches. Then, monotonic loading was applied to both the minor and major axes of the specimens. The finite element models were also generated and proved the accuracy of the test results. Using the proposed reinforcing system the flexural capacity of the upright sections was improved around either the major axis or minor axis. The 200 mm reinforcement type provided the best performance of the three types. The proposed reinforcing pattern enhanced flexural behavior and constrained irregular buckling and deformation. Thus, the proposed reinforcements can be a very useful and cost-effective method for strengthening all open CFS sections under flexural loading, considering the trade-off between flexural performance and the cost of using the method

Effects of Diethanolamine (DEA) and Glass Fibre Reinforced polymer (GFRP) on setting time and mechanical properties of shotcrete

© 2020 Elsevier Ltd By now, various accelerators have been used to accelerate the chemical reactions between cement and water to achieve a desired strength. This study investigates the effects of diethanolamine (DEA) as a less corrosive accelerator on the setting time and mechanical properties of fibre reinforced shotcrete (FRS). Glass fibre reinforced polymer (GFRP) was also used to improve the flexural and tensile strengths of shotcrete. In total, 76 different mix designs were prepared and tested to determine the setting time, flexural and tensile strength of shotcrete. The mixes were designed based on three influential parameters including GFRP, water/cement (w/c) ratio and the amount of DEA. According to the results, the flexural and tensile strengths of all specimens increased by adding 0.5% of the weight of GFRP. However, both tensile and flexural strengths showed an insignificant reduction by adding DEA to the mixes. The tensile and flexural strengths of specimens decreased slightly by adding DEA in the presence of GFRP. At a certain amount of DEA, the setting time increased twice with increasing the w/c ratio. The results showed a reduction in the shotcrete strength by using DEA. Thus, in the case where both the setting time and shotcrete strength are of great importance, the optimal DEA level is close to 0.3% of the dry weight of cement and 0.5% GFRP

The impact of long-term curing period on the mechanical features of lime-geogrid treated soils

One problem that has always been a challenge for geotechnical engineers is construction on problematic and soft soils. Traditional methods of lime and cement stabilisation can be used to treat soils with these properties. The main drawback of lime addition to the clayey soils is a significant loss in ductility of lime-treated soils. Using ductile materials such as geogrids in lime-treated soils is one of the most effective ways to increase the soil ductility. Therefore, the effect of geogrids and lime on unconfined compressive strength (UCS), failure strain (ɛf), secant modulus (Es), deformability indexes (ID), resilient modulus (Mr), bulk modulus (K), and shear modulus (G) of the treated soil was investigated in the current research study. The UCS test was carried out on modified specimens with geogrid and lime within 365 days curing period. The experimental results showed that adding geogrids and lime enhances the geotechnical characteristics of clayey soils, considerably. Finally, a simple mathematical model was developed to predict the features of the lime-geogrid treated clay