Analysis and Design of Steel-Concrete Composite Frame Systems
The lack of clear guidance regarding the value of elastic flexural rigidity (EI) that should be used in the analysis of steel-concrete composite columns is a significant unresolved issue that hinders the design of frame systems that include these members. The common approach of utilizing the rigidity of either the steel or the concrete only tends to be overly conservative. Other approaches that combine the rigidities have not been fully validated for use in strength and stability design procedures or for the determination of lateral deflections. To address this issue, research has been conducted to develop comprehensive recommendations for the elastic flexural rigidity of composite columns. A complimentary goal has been to validate common strength design procedures, including interaction diagrams, axial compression and bending moment anchor points, and analysis procedures to determine required strengths. In this paper, an assessment of current strength design methodologies is presented along with recommendations for potential improvements. Both the AISC Direct Analysis method and the ACI elastic second-order analysis method are investigated. INTRODUCTION The wide availability of structural analysis software packages that perform accurate geometric nonlinear analyses has made second-order elastic analysis design approaches very common in practice. Such design provisions exist for steel-concrete composite members in both the AISC Specification (AISC 2010b), as the Direct Analysis method, and the ACI Code (2011), as the second-order analysis method. However, neither methodology has yet been comprehensively assessed for validity and accuracy, as has been done in the past for structural steel (Kanchanalai 1977; Surovek-Maleck and White 2004) and for reinforced concrete (Hage and MacGregor 1974). This paper presents the results of a large parametric study that has been conducted to assess the current design methodologies with a particular emphasis on the elastic flexural rigidity (EI) recommended for analysis. 2605 Structures Congress 2014 © ASCE 2014
IJSRD-International Journal for Scientific Research & Development| Vol. 4, Issue 02, 2016 | ISSN (online): 2321-0613
Steel-Concrete composite constructions are nowadays very popular owing to their advantages over conventional Concrete and Steel constructions. Concrete structures are bulky and impart more seismic weight and less deflection whereas Steel structures instruct more deflections and ductility to the structure, which is beneficial in resisting earthquake forces. Composite Construction combines the better properties of both steel and concrete along with lesser cost, speedy construction, fire protection etc. Hence the aim of the paper is to compare seismic performance of a 3D (G+5) story RCC and Steel-Concrete Composite building frame situated in earthquake zone IV. All frames are designed for same gravity loadings. Beam and column sections are made of either RCC & Steelconcrete composite sections. Equivalent static method is used for seismic analysis. ETAB2015 software is used and results are compared. Comparative study concludes that the composite frames are best suited among concrete constructions in terms of materials and weight with better seismic behavior.
Novel polymeric hydrogel composites: Synthesis, physicochemical, mechanical and biocompatible properties
In this research study, novel hydrogel composite films were constructed using different ratios of poly (vinyl alcohol) (PVA)/kappa-carrageenan (KC) (PVA90/KC10%, PVA80/KC20%, PVA70/KC30%, PVA60/KC40%) crosslinked with glutaraldehyde (0.025%) and investigated their physicochemical characteristics such as mechanical, thermal, morphological, swelling behaviour, and cell viability. SEM and FTIR revealed that surface morphology changed to heterogeneous and the presence of molecular interaction among the polymers. PVA90KC10 and PVA60KC40 exhibited smaller and larger pores on surface respectively. The change in the proportion of PVA and KC also triggered the tensile strength (Ts) of the film and the highest Ts observed were 21.60 MPa for PVA60KC40. Moreover, the thermal analysis showed three-phase degradation, and an increase in KC40 concentration results inversely proportional to a decrease in the rate of thermal degradation. Further, swelling and in-vitro biodegradation study confirmed the enhanced perseverance of water uptake for PVA60KC40 (286%) due to pores structure of the hydrogel film and PVA and KC alone degraded faster as compare to other films results suggested higher concentration of PVA90KC10 showed lower degradation rate and highest for PVA60KC40 about 6% and 22% respectively. Further, the cell viability was studied with MTT assay method by using NIH3T3 and HEK-293 cells for biocompatibility study revealed NIH3T3 cells were more biocompatible than HEK-293 and cell viability percent for PVA60KC40 showed the highest cell attachment about 99%. Overall corroborating data obtained from the study attested to the average swelling, appreciable mechanical characters, good interaction between molecules, and cell viability of the constructed PVA/KC hydrogel film, these all characters pave to be used as a potential template for biomedical applications such as tissue engineering and drug delivery.