American Society of Civil Engineers


Long-Term Behavior of Composite Beams under Positive and Negative Bending. II: Analytical Study


by Jiansheng Fan, (corresponding author), (Associate Professor, Dept. of Civil Engineering, Key Laboratory of Structural Engineering and Vibration of China Education Ministry, Tsinghua Univ., Beijing 100084, China E-mail: fanjsh@tsinghua.edu.cn), Xin Nie, Ph.D., (Student, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China), Quan Li, (Master Student, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China), and Quanwang Li, (Assistant Professor, Dept. of Civil Engineering, Tsinghua Univ., Beijing 100084, China)

Journal of Structural Engineering, Vol. 136, No. 7, July 2010, pp. 858-865, (doi:  http://dx.doi.org/10.1061/(ASCE)ST.1943-541X.0000176)

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Document type: Journal Paper
Section Heading: Metal and Composite Structures
Abstract: The creep, shrinkage, and cracking of concrete may induce time-dependent changes in the stresses, internal forces, and deflections of steel-concrete composite beams. This paper presents an analytical model to consider these effects in analyzing the long-term behavior of composite beams under service loads using the step-by-step procedure. Under negative moments, the model accounts for the cracking, stress relaxing, tension stiffening, creep, and shrinkage of concrete. Meanwhile, a method is proposed to calculate the maximum crack width of the concrete slab by considering the shrinkage and creep effects. Four composite beams continuously loaded for about 3 years were analyzed using the proposed model. A good agreement is observed between the experimental results and the calculations by the proposed model. A discussion is also made about the aging coefficients in the age-adjusted effective modulus method under different loading conditions.


ASCE Subject Headings:
Shrinkage
Creep
Cracking
Composite beams
Bending
Serviceability

Author Keywords:
Shrinkage
Creep
Effective modulus
Cracking
Composite beams
Serviceability