Metin Husem

The effects of bond strengths between lightweight and ordinary aggregate-mortar, aggregate-cement paste on the mechanical properties of concrete

The interfacial zone between cement paste and aggregate plays a critical role in determining mechanical properties of concrete. In this study, the effects of bond strength between aggregate and mortar, aggregate and cement paste on the mechanical properties of lightweight and ordinary concrete were examined. The flexural and compressive strengths of specimens of lightweight and ordinary mortars, the aggregate used in production of lightweight and ordinary concrete, and pure cement paste were experimentally determined together with the bond strength between aggregate and mortar, aggregate and cement paste. In experimental studies, natural lightweight aggregate and normal aggregate with Portland cement were used. Some basic expressions obtained from using aggregate strength, mortar strength, cement paste, and bond strength were given to estimate the compressive strength of lightweight and ordinary concretes.

Determination of rectangular stress block parameters for high performance concrete

Despite so much research on high performance concrete, the properties of this concrete are not known as well as those of ordinary concrete. There have been a lot of equations, rules and suggestions in the codes which are used in the design of reinforced concrete and prestressed concrete structures. They are obtained from experimental studies made on concrete that have compressive strength of less than about 40 MPa. It is not exactly known whether they could be used in the design of structures constructed by using high performance concrete. Therefore in this study, stress-strain and equivalent block parameters were obtained from experimental stress-strain diagrams for calculation of high performance reinforced concrete beams in flexure. The conclusions obtained from this study showed that determined rectangular stress block parameters can be used in the design of high performance reinforced concrete members in flexure.

Cyclic behavior of GFRP strengthened infilled RC frames with low and normal strength concrete

Abstract This paper presents the experimental behavior of plane, non-strengthened and glass fiber reinforced polymer (GFRP) strengthened infilled reinforced concrete (RC) frames with low strength concrete (LSC) and normal strength concrete (NSC) under lateral reversed cyclic loading. For this purpose, eight full-scale, one-bay, one-storey plane and infilled (brick and aerated concrete blocks which are commonly used in RC construction) RC frames with LSC and NSC were produced and in-plane lateral loading tests were carried out. Test results indicate that infill walls considerably change the behavior of frames by increasing rigidity and load carrying capacity. By contrast, GFRP fabric used for strengthening of infilled RC frames improves ductility, load carrying and energy dissipation capacity of infilled frames with LSC and NSC as well. After all the test results were evaluated together, a GFRP strengthened brick infilled frame demonstrated the best performance under cyclic lateral loading.

Effect of Construction Errors on the Snow-Induced Failure of a Tribune’s Columns and Roof

AbstractThis paper aims to present an investigation about the effect of construction errors on the snow-induced failure of tribune columns and roof. The structure, located in the town of Kalkandere...

The behaviour of high-strength reinforced concrete columns under low eccentric loading

In this study, the change of the behaviour of high-strength reinforced concrete (HSRC) columns under axial and eccentric load based on the ratios of transversal and longitudinal reinforcements was investigated. To do this, 2100 mm height and 200 mm × 300 mm cross-sectional sizes reinforced concrete columns which have different transversal and longitudinal reinforcement ratios were produced with high-strength concrete. On these produced columns, two different eccentricity (e = 25 mm and e = 50 mm) and axial (e = 0) loadings were done. The experimental and theoretical moment–curvature (M–K) relations were determined and compared with each other. Test results showed that in the HSRC columns, the ratio of longitudinal reinforcement did not changed the fracture type which was brittle, but when the ratio of transversal reinforcement increased, the type of fracture was changed. The M–K relation obtained from the experiments and the M–K relation calculated theoretically were in harmony. This showed that the material model which was used to determine theoretical M–K relation was suitable for HSRC.

THE EFFECT OF FRACTURE AND CRACK GROWTH OF STEEL AND POLYPROPYLENE FIBERS IN THE ORDINARY AND HIGH STRENGTH CONCRETE

Today, high performance concrete can be produced as easily as normal strength concrete. Concretes are expected to have ductile behavior and have compressive strength, as well. In the recent years, in order to have ductile behavior, researchers have started to strengthen concrete using fibers and have done lots of researches. In this study, normal and high strength concrete with steel and polypropylene fiber are produced, the compressive strength and the tensile strength in split of these concrete is investigated and the fracture energy and crack distribution of notching samples are examined.