Simplified model of creep and shrinkage effects in reinforced concrete flexural members

Measurements made on a long span reinforced concrete arch culvert under 7.3 m (24 ft) of silty clay backfill were compared with results from finite-element analyses of the soil-structure system using the CANDE finite-element code. The culvert strains and deflections and the soil pressure on the culvert were measured during construction and during the following 2.5 years at three instrumented cross sections. The CANDE program was modified to account for the effects of concrete creep and shrinkage strains after it was noted that the measured postconstruction culvert deflection and strains increased significantly whereas the measured soil pressure on the culvert remained relatively constant. Good agreement was generally obtained between measured and calculated values of the culvert strain and deflection and the soil pressure during the entire monitoring period after the code was modified.

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Simplified Modeling Research of Reinforced Concrete Based on the Dynamic Stiffness Equivalence

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.458 ◽

2012 ◽

Vol 446-449 ◽

pp. 458-462

Author(s):

Jie Hu ◽

Jia Quan Feng ◽

Xi Nong Zhang

Keyword(s):

Reinforced Concrete ◽

Reference Model ◽

Dynamic Stiffness ◽

Optimization Method ◽

Simplified Model ◽

Response Analysis ◽

Reinforced Concrete Structure ◽

Optimization Function ◽

Nature Frequency ◽

Simplified Modeling

This paper proposed a simplified modeling method of reinforced concrete based on the equivalence of dynamic stiffness, the parameters of simplified model were modified to make the error of nature frequency between reference model and simplified model as small as possible, and an appropriate optimization function was designed. The essentiality of the proposed method is parameter optimization, with the advantages such as fewer elements and calculation assumption. The numerical simulation result indicated that this optimization method is suitable for the dynamic response analysis of complicated reinforced concrete structure.

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Minimum thickness of concrete members reinforced with fibre reinforced polymer bars

Canadian Journal of Civil Engineering ◽

10.1139/l01-021 ◽

2001 ◽

Vol 28 (4) ◽

pp. 583-592 ◽

Cited By ~ 3

Author(s):

Amin Ghali ◽

Tara Hall ◽

William Bobey

Keyword(s):

Reinforced Concrete ◽

Minimum Thickness ◽

Reinforced Polymers ◽

Flexural Members ◽

Steel Reinforced Concrete ◽

Concrete Members ◽

Reinforced Polymer ◽

Steel Bars ◽

Fibre Reinforced Polymer ◽

Frp Bars

To avoid excessive deflection most design codes specify the ratio (l/h)s, the span to minimum thickness of concrete members without prestressing. Use of the values of (l/h)s specified by the codes, in selecting the thickness of members, usually yields satisfactory results when the members are reinforced with steel bars. Fibre reinforced polymer (FRP) bars have an elastic modulus lower than that of steel. As a result, the values of (l/h)s specified in codes for steel-reinforced concrete would lead to excessive deflection if adopted for FRP-reinforced concrete. In this paper, an equation is developed giving the ratio (l/h)f for use with FRP bars in terms of (l/h)s and (εs/εf), where εs and εf are the maximum strain allowed at service in steel and FRP bars, respectively. To control the width of cracks, ACI 318-99 specifies εs = 1200 × 106 for steel bars having a modulus of elasticity, Es, of 200 GPa and a yield strength, fy, of 400 MPa. At present, there is no value specified for εf; a value is recommended in this paper.Key words: concrete, cracking, deflection, fibre reinforced polymers, flexural members, minimum thickness.

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