• Journal of Korean Society of Steel Construction
• /
• v.25 no.4
• /
• pp.369-377
• /
• 2013

The age-adjusted effective modulus method has been known to provide more precise assessment than the traditional Yassumi method for long-term behavior estimation of prestressed composite girders. The age-adjusted effective modulus method, however, involves complicated calculation, thereby making the Yassumi method more prevalent in actual design. This study presents rational approaches to revise creep coefficients for the Yassumi method by using parametric study results obtained from the age-adjusted effective modulus method.

• Journal of Korean Society of Steel Construction
• /
• v.24 no.5
• /
• pp.571-582
• /
• 2012

Prestressed composite girders provide efficient composite action by applying prestress to the sub-encasing concrete. In this study, an enhanced prestressed composite girder with forms suspended from the steel girder is utilized. Long-term behavior of the prestressed composite girder is estimated using age-adjusted effective modulus method, which is verified experimentally using measurements obtained from an in-service bridge. Then, parametric study is carried out to investigate the influences caused by ambient temperature, humidity, prestressing and concrete casting date.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.175-176
• /
• 2009

An improved column shortening analysis method which can be used in designing the horizontal members has been proposed. If you use this analysis method which is used effective modulus method by EMM or AEMM, you will get more exactly moments on the horizontal members.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.2A
• /
• pp.243-247
• /
• 2008

An analytical approach to calculate time-dependent stresses and strains in initially cracked reinforced concrete section with biaxial bending was proposed. The method utilized the aging coefficient approach of Bazant and the linear creep theory. The position of neutral axis and strain and stress distributions of cracked section after creep and shrinkage were determined from the requirements of strain compatibility and equilibrium of a section. With this proposed algorithm, examples were given for rectangular section and a comparative analysis for stress and strain was also made.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.1
• /
• pp.1-12
• /
• 1994

This paper deals with the time-dependent analysis of reinforced and prestressed concrete beams. Based on the age-adjusted effective modulus method, the structural behavior in accordance with time is analyzed using the force equilibrium and strain compatibility condition within a typical section. Unlike most of presented approaches adopting some assumptions, such as non-cracking of concrete and consideration of steel effect as a transformed concrete area only, more accurate results can be obtained at all loading conditions since all materials are considered together so as to be maintained their given properties and the cracking effect is included at the same time. Several parameter studies are conducted with the objective to identify the significance of various effects on the time-dependent response of concrete members, i.e., stress re-distribution of each material and occurrance of long-term deflection, etc. Moreover, the obtained results can be used at design and/or construction stage for the purpose of more accurate prediction of structural response with time.