how to design slab in staad?
You need to model the slab using plate elements. To design the slab, in the modelling mode, go to Design > Concrete > specify the design parameters > click on Commands > select Design Slab/Element and assign it to the required plate elements. In the output, you can view the slab design results.
There are 3 aspects involved.
1) Generating the model consisting of the slab and other entities such as beams and columns.
2) Analyzing the model to obtain the displacements at the nodes, forces and moments in beams and columns, and stresses in the plate elements used to model the slab.
3) Designing the slab to obtain the reinforcing details
1) Generating the model
The slab itself should be defined using a mesh of plate elements. There are various methods available for creating a plate mesh. Tutorial 3 of the Getting Started manual shows four methods of which two involve mesh generation.
If you plan to include beams and columns in the model, those should be defined using frame members (line entities).
With this, the geometry of the model will be complete. Go on to assign properties to the members, thickness for the elements of the slab, supports for the structure, and loads. The three tutorials in the Getting Started manual all illustrate the steps for doing these.
2) Analysing the model
After you complete the model generation, run the analysis. Again, any of the tutorials in the Getting Stared manual show you the procedure. After the analysis is completed, go to post-processing, view the displacements, member forces and plate stresses to ensure that they look reasonable. Also, check the output file for warnings or errors, and if there are any, make the necessary changes to avoid those. After you get a successful analysis run, come back to the Modeling mode.
3) Designing the slab
Method 1 : As Suro mentioned, this method involves specifying design parameters such as Steel and concrete strength (FYMAIN, FC), Clear cover for the bars, etc. and the "DESIGN ELEMENT" command from the Design page of the STAAD Modeling mode. Those instructions, called parameters and design commands, will then get embedded into the STAAD input file along with the geometry, properties, supports, loads and such data that you specified while creating the model. You will then have to run the analysis again. At that time, the program executes the instructions for designing individual elements of the slab.
This method is just an approximate way to find out if the thickness of the slab is sufficient to carry the loads. It does not include checks such as oneway and punching shear, bond, reinforcement bar details, etc. In the Application examples section, example 9 illustrates this method. It is something similar to a "code check" for individual elements comprising the slab. It does not do a full-scale RC detailing of the slab in its entirety.
Method 2 : Using the Concrete Design item that is available from the Modeling Mode. After the analysis is completed, enter the Concrete Design mode. Once inside that mode, the elements that constitute the slab have to be selected and you have to form a slab which subsequently have to be designed using the facilities of this mode. This is also called the "RC Designer" mode. For help on designing a slab using this method, go to Help-Contents-Graphical Interface Help- Concrete Design Mode-Examples-BS8110 British Code Examples-Slab Design
Method 3 : Using RAM Concept - a powerful slab design software offered by Bentley. This is a program exclusively for designing slabs - elevated floor slabs (RC and post-tensioned) and foundation slabs. You will require a license for this program to use this feature. The procedure for designing a slab using this method, go to
Help-Contents-Graphical Interface Help-Advanced Slab Design Mode
Elsewhere in this forum, you will find numerous discussions on designing slabs using RAM Concept.
So, using this method, the slab in the STAAD.Pro model is exported to RAM Concept and the design of that slab is done by RAM Concept.
sir how to calculate the plate load?
what are the loads to be taken?
The document that describes the specifications and scope of your building project should tell you what loads to consider, or, what documents to use to obtain that information. Your own judgment should also be a guide in this matter. For example, for a water tank, the bottom slab should be designed for its own weight, plus, the weight of the water it supports, etc. The side walls of the tank should be designed for hydrostatic pressure due to that height of water. Commonsense tells us that the structure should be designed for wind, seismic, etc.
For buildings, the building code applicable for the project should tell you the amount of live load to consider on each floor and roof. These loads are usually specified in terms of pressure, such as for example, 400 kg/sq.m. Additional loads such as equipment on the floors too need to be obtained in terms of pressure (load per unit area). Once you have the various pressure values, you can apply them on the plate elements of the model as a uniform pressure on those elements. Hydrostatic pressure can be applied using STAAD's trapezoidal load facility for elements.
If your building structure is in the USA, refer to the document named ASCE 7 - Minimum Design Loads for Buildings and Other Structures. Similar documents are available for the Eurozone and for various countries.
I had the same question. Thank you very much for clearing that to me. I have another question. If I want to design only the beams and columns then will adding the slab weight as dead load suffice?