Square and rectangular hollow sections are generally produced either by hot-rolling or coldforming. Cross-sections of nominally similar geometries, but from the two different production routes may vary significantly in terms of their general material properties, geometric imperfections, residual stresses, corner geometry and material response and general structural behaviour and load-carrying capacity. In this paper, an experimental programme comprising tensile coupon tests on flat and corner material, measurements of geometric imperfections and residual stresses, stub column tests and simple and continuous beam tests is described. The results of the tests have been combined with other available test data on square and rectangular hollow sections and analysed. Enhancements in yield and ultimate strengths, beyond those quoted in the respective mill certificates, were observed in the corner regions of the cold-formed sections -these are caused by cold-working of the material during production, and predictive models have been proposed. Initial geometric imperfections were generally low in both the hot-rolled and cold-formed sections, with larger imperfections emerging towards the ends of the cold-formed members -these were attributed largely to the release of through thickness residual stresses, which were themselves quantified. The results of the stub column and simple bending tests were used to assess the current slenderness limits given in Eurocode 3, including the possible dependency on Gardner, L., Saari, N. and Wang, F. (2010) Comparative experimental study of hot-rolled and cold-formed rectangular hollow sections. Thin-Walled Structures. 48(7), 495-507. 2 production route, whilst the results of the continuous beam tests were evaluated with reference to the assumptions typically made in plastic analysis and design. Current slenderness limits, assessed on the basis of bending tests, appear appropriate, though the Class 3 slenderness limit, assessed on the basis of compression tests, seems optimistic. Of the features investigated, strain hardening characteristics of the material were identified as being primarily responsible for the differences in structural behaviour between hot-rolled and coldformed sections.

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Research on Engineered Cementitious Composites (ECC) is overwhelming owing to its wide structural applications that can serve multi-functional purposes in civil and nvironmental infrastructures. Compared to other high-performance fiber reinforced concrete, ECC yields superior tensile ductility and multiple cracking behaviors when subjected to tensile loadings even with low to moderate volume of fibers. This paper presents the flexural properties of ECC made of cement, an industrial by-product, such as ground granulated blast-furnace slags (GGBS), local silica sand, polyvinyl alcohol (PVA) fiber, water, and superplasticizer (SP). Two series of ECC mixtures (ECC-G50 series and ECC-G60 series) and one control mixture were designed. The effect of two different fiber contents in volume fraction was investigated for the two series of ECC mixtures. The compression and flexural tests were conducted on ECC and control specimens after 28 days of curing. A compression test revealed that almost all ECC mixtures improved compressive strength between 20% to 30% compared to the control specimens. In addition, all ECC plate specimens demonstrated excellent strain-hardening states (i.e., displacement capacity at least ten times greater than the control specimens) and multiple fine-cracks failure modes after the three-point bending test. The increase in fiber content slightly reduced the compressive strength but enhanced the flexural behavior of the ECC-G50 series. However, this observation is not discovered in the ECC-G60 series. Outcomes of this research assist material scientists on the content of PVA fiber and GGBS used in making ECC.

The flexural behaviours of reinforced concrete (RC) beams incorporating steel and polypropylene fibres under four-point bending test is examined in this paper. A total of nine beam specimens were designed, cast and tested under flexural loadings. Three types of concrete mixture – plain, concrete with steel fibres and concrete with polypropylene fibres – were employed in this study. Fibre content is fixed at 3% by the weight of sand as sand replacement for both mixtures containing either steel or plastic fibres. Compression tests were also conducted at 7, 14 and 28 days for twenty-seven concrete cubes prepared using the three mixtures. Comparisons of results were done in term of compressive strength, ultimate flexural load and deflection capacity. The crack pattern and failure mechanism of RC beams subjected to four-point bending are discussed. Finally, the effect of steel and polypropylene fibres on the flexural behaviour of RC beams are justified.

This study aims to conduct the Ultrasonic Pulse Velocity (UPV) test and compressive strength test of Steel Fiber Reinforced Concrete (SFRC). This paper also examines the correlation of UPV test data and compressive strength test data for SFRC specimens. The experiments were carried out with the same value of the water-cement ratio, superplasticizer but different fiber volumes of steel fiber. Twelve prism sizes 100mm x 100mm x 500mm were casted and 0.5%, 1.0%, and 1.5% of steel fiber reinforced concrete were added and the prisms undergone curing for 7, 14 and 28 days. The highest value of the UPV test at the x-axis is SFRC-0.5%, 6.26 km/s at seven days and 6.8377 km/s at 14 days. The highest value of the UPV test at the y-axis is SFR-0.5%, 6.68 km/s at seven days and 6.34 km/s at 28 days. Nevertheless, the grading is still considered excellent concrete quality based on BS1881. The highest value of compressive strength is SFRC-1.0%, 193.2 MPa at 14 days. The R-squared value for the correlation coefficient between UPV result and the compressive strength result at the x-axis and y-axis is 0.9963 and 0.9966 respectively. The non-linear models show high regression coefficient of R-squared close to 1.00, which means the parameters are strongly correlated. The correlation equation obtained can be used to predict compressive strength based on UPV data for steel fiber volume fraction up to 1.5%. Thus, it can be concluded that percentage of steel fiber added, affect the strength of the tested concrete specimens and the optimized value of steel fiber added is at 1% in this study.

This experimental study investigatedsteel fiber reinforced concrete (SFRC) specimen’s performance by using to X-Ray Fluorescence (XRF) test, Flexural Strength test, Compressive Strength test and Rebound Hammer test. The experimental result of the compressive strength test was further analyzed by 3D Analysis using Stat-Ease Design-Expert V13 to correlate the compressive strengths to the elemental composition of the concrete structure. The result showed that the amount of Calcium Oxide (CaO) in the sample was lower than the composition of Ordinary Portland Cement (OPC) used. Thirty-six (36) beam samples of 100mm x 100mm x 500mm size and twelve (12) cube samples of 100mm x 100mm x 100m size were prepared with different percentages of steel fiber (0.5%, 1.0% and 1.5%) to determine the optimum dosage. All samples were tested at 7, 14 and 28 days. It can be concluded that the analysis shows a low significant effect at an early aged concrete but showing a slightly increased in compression and flexural strength at a later age. The results also showed that the addition of steel fibercauses the reduction of slump value (workability). Recommended optimum percentage range of steel fiber addition in concrete is proposed. The relation among rebound hammer number, compressive strength and flexural strength of the specimens was also discussed.

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