Design for SLS according to fib Model Code 2010

Abstract

This paper provides an overview of serviceability specifications given by the fib Model Code for Concrete Structures 2010 (fib MC2010 [1]). First, the reasons behind crack control and deflection control are discussed, then specific design rules are provided. Simple rules as well as detailed models are also presented. Numerical examples are provided in order to assist in the application of the design recommendations for crack control and deflection control (reinforced and prestressed concrete elements).Simple rules mean indirect control of cracking or deflections without calculations. Indirect crack control may include limitation of stresses and selection of maximum bar diameter or maximum bar spacing. Indirect deflection control normally means limiting the span‐to‐depth ratio.Detailed models are based on physical and mathematical approaches to cracking and deflections. The design crack width is expressed as the maximum bond transfer length multiplied by the mean strain between cracks. Deflection analysis can be provided by integrating curvatures or by using a simplified or refined method. Vibrations and numerical modelling of cracking are also briefly discussed.

Quality assessment of material models for reinforced concrete flexural members

“…In order to clarify the choice of the reference model, for the bending moment loading condition the analysis by QUAST [34] emphasises the model with the modified steel strain to be an more adequate model in comparison with other tension stiffening models and experimental results. In general, a comparison by BALÁZS et al [35] between the results of fracture mechanics approach and the more simplified tension stiffening based models illustrate a generally applicability of the simplified models for predicting the average response of a reinforced concrete member.…”

Post‐installed reinforcement connections at ultimate and serviceability limit states

“…-The slip resulting from the cast-in side of the bar in the new concrete is calculated based on equilibrium and compatibility requirements according to the state of the art in modelling bond-slip behaviour, with the main difference being, however, that the adhesive bond strength at the interface replaces the concrete tensile strength. As shown in the following derivation, after some simplifications this ends up basically in the state-of-the-art relationship for the calculation of crack widths as presented, for example, in fib Model Code 2010 [11,12]. -The slip of the post-installed side of the bar is evaluated on the basis of pullout tests.…”

“…Compatibility requires that (12) Rearranging and introducing ρ eff = A s /A c,eff and α e = E s /E cm results in (13) This formula can be simplified to (14) which basically corresponds to fib Model Code 2010 [11], formula 7.6-6 (with σ ct instead of f ctm ). This tension is introduced into the concrete by bond between steel and concrete assuming the average bond strength τ bm .…”

Nachrichten des Verbandes Biologie, Biowissenschaften & Biomedizin in Deutschland

“…The mechanical characteristics of the concrete were compressive strength 46 MPa, elastic modulus 33 GPa and flexural tensile strength 3.5 MPa. The concrete strains due to free drying shrinkage ( ϵ cs [8]) were measured on 75 × 75 × 275 mm concrete prisms in accordance with AS1012.13 [9] over a six‐month period. During the tests, the prisms were stored in the same humidity and temperature conditions as the beams.…”

“…Some experimental results are reported, showing how the conclusion of Caldentey et al [5] should be modified when taking account of time‐dependent effects. Experimental results obtained during both short‐ and long‐term tests are compared with predictions made using the provisions of the fib Model Code for Concrete Structures 2010 [8].…”