Material (Concrete Beam)

Last modified by Fredrik Lagerström on 2021/08/06 13:25

The material input is separated in four tabs, Material, Reinforcement details, Calculation settings and Bar shortening.

Material data

In the material dialog box all material strength input is assembled. By pressing one of the [...]-button a dialog box for showing the complete data of the selected material or for defining a user defined material is opened.

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General

Under the header General, conditions that affect the calculation are stated. Exposure class and Life class are defined and affect code checks where relevant. The options Quality control and reduced deviations and Reduced or measured geometrical data can be checked. The two latter options together with the option Low strength variation, see below, changes the partial factors for materials according to EN 1992-1-1 Annex A A2.1 and A2.2.

Concrete

Concrete strength class can be defined by selecting from the list. Current design values are shown. If the option Low strength variation is checked together with one or both of the two options described above the partial factor for concrete will be changed according to EN 1992-1-1 Annex A A2.1 and A2.2.

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By pressing the [...]-button beside the strength class the complete current data is being shown, as is a graphic presentation of the stress-strain diagram. The values in the material data are available for changes when the option Create new is chosen.

Design values Reinforcement

In the Reinforcement dialog boxes type of reinforcement for bottom- and top bars as well as stirrups can be defined by selecting from lists. Current design values as well as current diameters are shown.

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By pressing the [...]-button beside the strength class the complete current data is shown, as is a graphic presentation of the stress-strain diagram. The values in the material data are available for changes when the option Create new is chosen.

National considerations

92874_-_britain_flag_great.png British Annex

For the British Annex also the w/c ratio is defined depending on current exposure class. This option affects the required cover according to Table NA.2 and  NA.3 in the British Annex.

92848_-_denmark_flag.png Danish Annex

In the Danish Annex environmental classes are defined instead of exposure classes. The relations between these are the following:

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For the Danish Annex also the Inspection Level should be defined which affects the partial factor for materials.

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If the option Prefabricated elements is checked the partial factors for material is changed. The options Reduced or measured geometrical data and Low strength variation are not used in the Danish Annex.

92865 - finland flag.png Finnish Annex

For the Finish Annex also the Construction class are defined which affects the required cover.

Reinforcement details

In the Reinforcement details dialog box bar diameters, cover of reinforcement, min spacing between bars and so on used to distribute calculated amounts of
reinforcement can be defined.

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Main bar details

The diameter for bottom and top reinforcement are defined. If standard reinforcement is chosen the diameters are the ones available for that type. For non-standard reinforcement the available diameters are 1-99 mm. Further on, the covers at bottom, top and side are defined together with allowed distances between bars in the same layer and for different layers.

How the reinforcement is positioned is also influenced by the options Vibration space and Largest aggregate size. The option Cover deviation represents the part of the total cover called Δcdev according to EN 1992-1-1 4.4.1.3.

The program will choose minimum values (displayed with blue print) for the current diameter and code with the Code value button.

When the Code control option of input data has been activated the chosen values will be controlled, and compared with, existing rules for the current code.

Secondary bar details

The user can chose to calculate completely without stirrups and will then get a warning if the shear capacity is not adequate. The calculation will then be
performed according to EN 1992-1-1 6.2.2.

If stirrups are used the diameter is chosen, the angle between stirrup and beam axis and the minimum allowed distance between the stirrups.

Finally the user defines if minimum shear reinforcement according to EN 1992-1-1 9.3.2 should be considered. If activated this option will also be considered if
calculation without shear reinforcement is chosen, see below.

Note! Even if no shear reinforcement is required on basis of the design shear calculation, minimum shear reinforcement should nevertheless be provided except for slabs and members of minor importance, see EN 1992-1-1 6.2.1 (4). As default minimum reinforcement will be provided.

Calculation settings

In the Calculation settings dialog different options governing the calculation can be set.

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Design settings

The user can define if compression reinforcement, if needed should be used or not.
The user can define if minimum bending reinforcement according to EN 1992-1-1 9.2.1.1 or 9.3.1.1 should be considered. If the structure can be considered as
secondary where risk of brittle failure can be accepted then a limited amount of minimum reinforcement can be used according to 9.2.1.1 and 9.3.1.1.
The user can define if the special rules for monolithic constructions according to EN 1992-1-1 9.2.1.2 should be considered.

Concrete section iteration settings

Input for the iterative section calculation can here be adjusted if needed.

SLS settings

The user can chose between two or three different crack criteria’s in the Seviceability Limit State.

According to EC2 7.1 (2) the value of the concrete tensile strength fct,eff may be taken as fctm or fctm,fl.
The latter may be used for pure flexural stress. If tensile stresses, also those caused by shrinkage or thermal effects is present fctm should be used.

National considerations

92997_-_flag_sweden.png Swedish annex

According to the Swedish national annex (7.3.2.4) a third crack criterion can be used.

fct,eff = fctk / ζ

Where ζ is a safety factor for cracking which depends on environment and age of structure (EN1992-1-1 7.3.2 (4), table 7.2 (S)).

Shear calculation settings

Cot θ is defined where θ is the angle between the concrete compression strut in the imagined truss model and the beam axis.
The value affects the amount of required shear reinforcement according to EN 1992-1-1 6.2.3 and can be chosen between:

1,0 {\displaystyle \leq } cot θ {\displaystyle \leq } 2,5
The default value is 2.5 which means the smallest amount of shear reinforcement but also the smallest value for VRd,max which is the largest shear force value allowed for the beam.

The user can choose between shear calculation with shear reinforcement according to EN 1992-1-1 6.2.3 and without shear reinforcement where this is allowed according to EN 1992-1-1 6.2.2. For the latter option it is also possible to chose Enhanced shear strength near supports.

Bar shortening

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Method

If curtailing of the reinforcement is chosen, see below this can be done layer by layer or bar by bar.

Precision

This option decides how the bar lengths presented graphically should be rounded off.