Applied Mechanics and Materials Vol. 802

Abstract: Triangular web profile (TriWP) is a structural steel section made of two flanges connected to a web plate of triangular profile. The ability of TriWP to resist lateral–torsional buckling (LTB) is one of the most important criteria considered in the design of this steel section. This study examined the LTB behavior of TriWP steel section and determined the buckling moment resistance (M_b,Rd) for TriWP. Beam specimens were analyzed using a four-point bending test. Four types of specimen sizes were used: 200 mm × 100 mm × 6.3 mm × 6 mm; 200 mm × 100 mm × 9 mm × 6.3 mm; 200 mm × 100 mm × 8 mm × 6 mm; and 200 mm × 100 mm × 6 mm × 5 mm sections. Testing results for all specimen sizes showed that the values for M_b,Rd of the TriWP steel sections were higher than those of the flat web section. The percentage difference of M_b,Rd from the experimental results for all specimen sizes ranged from 10.38% to 17.37%. The percentage difference of M_b,Rd of the experimental and design values based on manual calculation by using Eurocode 3 ranged from 9.13% to 43.8%.

Abstract: An experimental investigation was presented in this paper on reinforced concrete box beams subjected to shear, torsion, and bending moment strengthened by carbon fiber reinforced polymer (CFRP). Eight box beams were cast and separated into two groups according to two different torque-to-shear and torque-to-bending moment ratios. Three box beams from each group strengthened by CFRP in different configurations and one control box beam were tested. The main parameters of this experiment were the different ratios and configurations, including U-jacket layers and U-jacket strips with or without longitudinal strips. The cracking and failure mode, effect of wrapping configuration, torsional capacity, and behavior of the different torque-to-shear and torque-to-bending moment ratios were studied in the paper.

Abstract: This study experimentally investigated the effect of nearby buildings, termed macroroughness on the tsunami loading. The hydraulic experiment was conducted in a 1 m x 1 m with 40 m long wave flume at a scale of 1:100. Nominal wave height of 40 mm was simulated in this study. Both the building model and the macroroughness elements consisted of 66 mm high solid blocks. Wave pressures exerted on frontal and back faces of the building model were discussed in detail in this paper. Experimental results showed that the macroroughness elements had a significant impact on tsunami loading in the inundation zone. Sheltering effect was exhibited by the seaward macroroughness elements, showing significant reduction in the front face pressures. With the presence of the landward macroroughness elements, the wave pressures at the back face of the building model increased significantly at the initial impact.

Abstract: This paper presents the impact energy of steel fiber concrete beams at first crack and failure with different replacement ratios of crumb rubber. The test was carried out using simple low velocity drop weight test rig for both normal concrete (NC) and steel fiber concrete (SFC). The crumb rubber with particle size of 1 – 2 mm was added with replacement ratios of 5%, 15%, and 25% by volume of fine aggregate. Six batches consisting of 6 beams (100x100x500 mm) containing 0.5% of hooked end steel fibers were tested under impact load in accordance with ACI Committee 544. The specimens were tested at the age 90 days after curing in water. The results show a reduction in the compressive strength for both NC and SFC with the incorporation of crumb rubber with greater reduction at higher crumb rubber content. However, the measured impact energy for both NC and SFC was found increasing with the crumb rubber replacement.

Abstract: The influence of silica modulus (Ms) on the compressive strength of alkali activated ultrafine palm oil fuel ash based mortar has been investigated. Two alkali activated mortar mixtures, S₁ and S₂ were prepared using sodium silicate (Na₂SiO₃) with initial silica moduli, Ms of 3.3 and 2, respectively. The Na₂SiO₃ was used in combination with sodium hydroxide (NaOH) with NaOH concentration of 10 M. The results indicate that the S₂ mortar mixture has higher strength than the S1 mortar mixture at all testing ages, with 28 day strength of 27.18 MPa and 32.8 MPa recorded by S₁ and S₂ mortar mixture, respectively. Hence, lower Ms leads to higher compressive strength. The higher compressive strength of S₂ is corroborated by the formation of more C-S-H as implied by the Fourier Transform Infra-red (FTIR) spectra analysis.

Abstract: Abstract. Vibration in building is one of the important problems which need to consider, especially in designing the floor. Floor vibrations are generally caused by dynamic loads applied particularly by human activity especially walking. Although it is specified as low level amplitude, walking induced vibrations can cause discomfort to human occupants and alarming for a certain items of precision sensitive equipment. This paper investigates the vibration response on floor performance due to one, three and five of people walking. Laser Doppler Vibrometer was used to obtain vibration data when people are walking. Further analysis was carried out by using finite element software package ANSYS to simulate the floor under vibration inputs to obtain natural frequency and mode shapes of the floor structure. The vibration data was then analysed in ModalV analysis to generate the vibration response. Then, the results were checked against the vibration criteria level guideline as a crude tool comparison. As a result, the numbers of people walking were influenced the floor performance, which indicated five peoples walking show the highest response up to ISO level due to vibration compared with one people walking.

Abstract: The influence of silica fume (SF) inclusion on the compressive strength development of high strength concrete (HSC) containing high volume of palm oil fuel ash (POFA) has been investigated. A HSC containing 100% ordinary Portland cement (OPC) and another HSC mix with 50% POFA as part of the binder were prepared. Due to the reduction in early strength of the HSC with the inclusion of high volume of POFA in the binary blended binder HSC, attempt was made to partially replace the OPC with SF at 5, 10, 15 and 20%, thus creating a ternary blended binder HSC. The results show that the compressive strength development of the HSC containing high volume of POFA was significantly improved with the inclusion of SF. The ternary blended binder HSC with 15% SF exhibited the highest increase in early age strength, even though it did not surpass the OPC-HSC, and it provided the highest strength at 7 and 28 days in comparison to other HSC mixes. Thus, ternary blended binder containing more than 60% supplementary cementitious material (POFA and SF) could be utilized to produce HSC.

Abstract: Lightweight constructions materials provide better thermal insulations properties for buildings. Using lightweight’s aggregates, such like wood particles is one of the most common ways for making lightweight building materials. The low cost and availability of wood particles made it the best ultimate materials preference in production of composites construction materials. Geopolymer, the alkali-activation cement-based materials have been proven can be used to produce lightweight materials. In additional, geopolymer possess excellent mechanical properties and significant reduction in CO₂ emissions compare to ordinary Portland cement. The use of environmentally friendly building construction materials has become increasingly important. This paper presents a review on producing lightweight building materials from geopolymer with wood particles as an aggregate.

Abstract: Addition or replacement of waste tyre in mortars and concretes in lightweight aggregate concrete composites are popular in concrete material research although the mechanical properties of the composite are reduced. Various research studies have been conducted in an effort to improve the mechanical properties of concretes and mortars containing waste tyre particles using chemicals and additives which lead to increase cost. This approach presents an economical and sustainable method, through adding oil palm fruit fibre (OPFF) at 0.5, 1%, and 1.5% by mass of cement content into the matrix and pre-treating the tyre crumb aggregate (0-40%) by volume with cement, in order to improve the properties of the composite. Mechanical properties including compressive strength, split tensile strength and flexural strength were measured on the mortar specimens. Results showed the addition of 0.5% OPFF in 10% treated tyre crumb mortar gives the best improvement in the mechanical strengths of mortar modified with treated tyre crumb.

Abstract: Analytical models and the basic preconditions for analysis of concrete and reinforced concrete structures should be established based on actual plastic properties of concrete and reinforcement, as well as consideration of presence of cracks in the concrete. It is known that the relationship between stress and strain in reinforced concrete is significantly different in the stage of work with cracks and without them. Development of computational method opens wide prospects in this direction. In this work the calculation of strength and definition of forces in constructive elements of structure from operational loadings are made on the basis of the finite element method. Analysis is carried out with the use of quadrangular isoparametric and beam elements by the method of level-by-level plasticization. Analytical model contains the nonlinear properties of concrete and reinforcement. Method and algorithm of calculation have been developed taking into account of real stress-strain diagrams from experiment. Method and algorithm of calculation of reinforced concrete designs include the limiting condition of deformation on the basis of known stress-strain diagram both for reinforcement and concrete. An example of analysis involving a tunnel structure for an underground station to determine internal forces using the proposed method was shown.