BEHAVIOUR OF HIGH STRENGTH CONCRETE COMPOSITE SLABS WITH DIFFERENT END ANCHORAGES

This study is performed to investigate experimentally the behaviour of steel deck composite slabs with different end anchorages. End anchorage as a type of shear connection for composite slabs plays an important role to prevent relative slip between concrete and steel deck. The presented composite slab specimens are made of high strength concrete and loaded at a specific shear span. Objectives of this study is to evaluate experimentally load carrying capacity, end slip, mode of failure, shear bond capacity, and the end anchorage contribution to the whole composite slab behaviour. Research also presents a comparison between the experimental results and the theoretical results derived according to m-k and partial shear connection methods included in these standards (BS 5950-4:1994, CSSBI S3-2003, and EC4 EN 1994-1-1:2004)

EXPERIMENTAL SHEAR RESISTANCE EVALUATION OF ORDINARY AND PERFOBOND Y-SHAPED SHEAR CONNECTORS

Composite structures refer to two load carrying structural members that are integrally connected and deforming as a single unique unit using shear connectors. The use of shear connectors enhances the development of longitudinal shear forces at the steel-concrete interface. The objective of this research is to study the structural behavior of a proposed separated Y-shaped shear connector. The suggested investigated Y-shaped shear connector is intended to be an improvement to the structural response of the conventional perfobond shear connector. Accordingly, this paper carries out six push-out tests on the separated Y-shaped shear connector according to EC4. The experimental work is performed in the Reinforced Concrete and Heavy Structures Laboratory at the Structural Engineering Department, Tanta University, Egypt. The key parameters affecting the behavior of the shear connector in the current investigation are the height, the thickness and the Y-shaping of the shear connector. Also, the effect of hole existence is investigated. Other parameters such as the length of the connector, the concrete strength and the slab geometry are kept the same for all specimens. Based on the performed tests, the results show that the proposed separated Y-shaped shear connector has higher shear resistance than that of the conventionalperfobond shear connector. Also, the proposed connector shows better ductile behavior than the conventional perfobond connector. Moreover, results proved that increasing the connector thickness has a significant effect on the connector behaviour by increasing its shear resistance. Furthermore, as the height of the connector increases, the shear capacity increases. Finally, from the presented results it is clarified that the proposed separated Y-shaped connector is better and more economical than the conventional perfobond connector

Shear Behaviour of Continuous Tapered Steel Plate Girders with Corrugated Webs

During previous years, so many attempts have been made to reduce the own weight of the steel members used in bridges, as well as reducing the cost of construction. One of these attempts is to use tapered (i.e. non-prismatic with varying depth) steel plate girders with corrugated webs (TPGCWS). The corrugated steel plates are widely used as structural elements in many structural applications because of their numerous favourable properties compared with traditional flat plates. Moreover, they have been used due to their aesthetical appearance, especially in the case of TPGCWs. So many researches have been made to investigate the shear behaviour of TPGCWS for the case of simple girder, to the author’s knowledge, no one has investigated the shear behaviour of TPGCWS for the case of continuous girder. So, the aim of this paper is to investigate the shear behaviour of TPGCWS for the case of continuous girder. Two experimental models have been tested to verify the finite element (FE) analysis and compare the experimental results with FE results and the existing design equations

Promotor methylation: Does it affect response to therapy in chronic hepatitis C (G4) or fibrosis?

Background and aim. DNA methylation plays a critical role in the control of important cellular processes. The present study assessed the impact of promoter methylation (PM) of some genes on the antiviral response to antiviral therapy and it’s relation to the presence of fibrosis in HCV-4 infected patients from Egypt.Material and methods. Clinical, laboratory and histopathological data of 53 HCV-4 infected patients who were subjected to combined antiviral therapy were collected; patients were classified according to their response to treatment and the fibrosis status. The methylation profiles of the studied groups were determined using the following genes: APC, P14ARF, P73, DAPK, RASSF1A, and O6MGMT in patients’ plasma.Results. O6MGMT and P73 showed the highest methylation frequencies (64.2 and 50.9%) while P14 showed the lowest frequency (34%). Sustained virological response (SVR) was 54.7%with no significant difference in clinico-pathological or laboratory features between the studied groups. PM of O6MGM was significantly higher in non-responders (p value 0.045) while DAPK showed high methylation levels in responders with no significance (p value: 0.09) andPM of RASSF1A was significantly related to mild fibrosis (p value: 0.019). No significant relations were reported between PM of any of the studied genes and patients’ features.Conclusion. PM of some Tumor Suppressor genes increases in chronic active HCV-4. However, only 06MGMT can be used as a predictor of antiviral response and RASSF1A as a marker of marked fibrosis in this small set of patients. An extended study, including more patients is required to validate the results of this preliminary study