Function
- Produce the serviceability check results for slabs.
Note
In order to use this function, Eurocode2:05 or ACI318-11,08,05 must be selected in Design > Concrete Design Parameter > Design Code.
Call
From the Main Menu select [Design] tab > [Type : Meshed Design] > [Perform/Result] group > [Slab Design] > [Slab Serviceability Checking]
Input
Load Combinations
Select a desired load case or load combination.
Click the ... Button to the right to enter new or modify existing load combinations. (Refer to "Static Load Cases / Combinations")
Serviceability Checking
Element: Display the serviceability check results using the internal forces calculated at each node of the element.
Avg. Nodal : Display the serviceability check results using the average internal nodal forces of the contiguous elements sharing common nodes.
Element : Depending on the selected option above (Element or Avg.Nodal), produce the serviceability check results for moments at each node of the elements that define the slab.
Width : Depending on the selected option above (Element or Avg.Nodal), produce the serviceability check results using the average of the moments in the slab elements that contain the selected node.
Top : Produce the serviceability check results for the bars in the top of the slab for negative moments.
Bottom : Produce the serviceability check results for the bars in the bottom of the slab for positive moments.
Both : Produce the maximum of the serviceability check results for the Top and Bottom bars.
Dir. 1 : Display the serviceability checking results for the reinforcing steel entered in Dir. 1.
Dir. 2 : Display the serviceability checking results for the reinforcing steel entered in Dir. 2.
Components
Deflection : Display the deflections
Uncracked : Calculate the deflection for the uncracked section and compare it with the allowable deflection.
Cracked : Calculate the deflection for the cracked section based on the cracked section analysis results and compare it with the allowable deflection.
Note 1
Cracking deflection can be evaluated after executing Perform Cracked Section Analysis.
Note 2
How to calculate the effective moment of inertia
The flexural rigidity of a beam may not be constant along its length because of varying amount of steel reinforcement and cracking at different sections along the beam. According to ACI Code 9.5.2.2 and 9.5.2.3, short-term deflection is computed using elastic methods of analysis considering effects of cracking and reinforcement on member stiffness, with the modulus of elasticity for concrete Ec=15100 √f’c and with the effective moment of inertia Iegiven as follows, but not greater than Ig.
and the cracking moment Mcr is given in the below Eq.
Ma = maximum moment in member at stage deflection is computed
Ig = moment of inertia of gross concrete section about centroidal axis, neglecting reinforcement
Icr = moment of inertia of cracked section transformed to concrete
fr = modulus of rupture of concrete = c 2 f ¢
yt = distance from centroidal axis of gross section, neglecting reinforcement, to extreme fiber in tension.
Moment of inertia of cracked section about neutral axis,
Creep : Long-term deflection due to creep effect
Stress Checking : Display the stress results in contour
Concrete : Display the compressive stress in the concrete
Reinforcement : Display the tensile stress in the reinforcement
Crack control : Display the crack results in contour
Crack Width : Display the value of crack width
Min As : Display the minimum area of rebar
Rebar Spacing : The minimum rebar spacing
Rebar Dia : The maximum rebar diameter
Deflection : Display the deflections
Uncracked : Calculate the deflection for the uncracked section and compare it with the allowable deflection.
Cracked : Calculate the deflection for the cracked section based on the cracked section analysis results and compare it with the allowable deflection.
Note 1
Cracking deflection can be evaluated after executing Perform Cracked Section Analysis.
Note 2
How to calculate the effective moment of inertia
Members which are expected to crack, but may not be fully cracked, will behave in a manner intermediate between the uncracked and fully cracked conditions and, for members subjected mainly to flexure, an adequate prediction of behavior is given by the following expression based on the sub clause 7.4.3 (3) in EN 1992-1-1:2004. Following factors including the effective moment of inertia by elements for each iteration step can be checked in "File Name_CSA.OUT" file.
Therefore Ieff (effective moment of inertia) can be calculated from the following equation.
Where,
Creep : Long-term deflection due to creep effect
Value : Display the values of the check results
Ratio : Display the ratio of the member force to the resistance
Operation
The Design Result Button : Produce the serviceability check results of slab elements in a text format.
Type of Display
Contour
Display the displacement of the model in contour.
The ... Button
Ranges: Define the contour ranges.
The Customize Range... Button : Assign the color distribution range of contour. Using the function, specific colors for specific ranges can be assigned.
Note
Contour Range Max/Min values can be larger than the max/min output values. If the Contour Range values exceed the output values, they are entered at Rank 0 and Rank 11.
Number of Colors : Assign the number of colors to be included in the contour (select among 6, 12, 18, 24 colors)
Colors : Assign or control the colors of the displacement contour.
Color Table : Assign the type of Colors.
The Customize Color Table Button : Control the colors by zones in the contour.
Reverse Contour : Check on to reverse the sequence of color variation in the contour.
Contour Line : Assign the boundary line color of the contour
Element Edge : Assign the color of element edges while displaying the contour
Contour Options : Specify options for contour representation
Contour Fill
Gradient Fill : Display color gradient (shading) in the contour.
Draw Contour Lines : Display color boundaries in the contour.
Draw Contour Line Only : Display only the colored boundaries of the contour.
Mono line : Display the boundaries of the contour in a mono color.
Contour Annotation : Legend or annotation signifying the ranges of the contour is displayed.
Spacing : Display the spacing for the legnd or annotation.
Coarse Contour (faster) (for large plate or solid model) : Represent a simplified contour for a large model using plate or solid elements in order to reduce the time required to represent a complete contour.
Extrude : Where plate elements or solid elements along a cutting plane are represented in contour, a three dimensional contour is created. The positive direction of the analysis results is oriented in the z-axis direction of the local element coordinate system.
The option is not concurrently applicable with the Deformed Shape option. Similarly, the option cannot be concurrently applied to the cases where the Hidden option is used to display plate element thicknesses or the Both option is used to represent Top & Bottom member forces (stresses).
Values
Display the nodal displacements in numerical values.
The font and color of the numbers can be controlled in Display Option.
The ... Button
Decimal Points : Assign decimal points for the displayed numbers
Exp. : Express as exponential
Min & Max : Display the maximum and minimum values
Abs Max : Display the absolute maximum value
Max : Display only the maximum value
Min : Display only the minimum value
Limit Scale(%) : Set the screen display limit for nodal displacements relative to the selected maximum or minimum value
Set Orientation : Display orientation of numerical values
Note
The default Decimal Points can be controlled in "Preferences".
Set Orientation = 0 horizontally displays the numerical values to the right of nodes or elements.
The orientation angle represents the counter-clockwise direction, which may be used to enhance the readability of the numbers.
Legend
Display various references related to analysis results to the right or left of the working window.
The ... Button
Legend Position : Position of the legend in the display window
Rank Value Type : Specify a type of values in the Legend and the number of decimal points.