If i model my project and add slab,what will be the difference if i dont generate plate mesh, after adding slab i add load and run analysis without generating mesh.
In Ram Concept? The program will always generate the mesh before you run the calculations. If there is a minor error in the first mesh generation, you may choose to skip re-meshing it again the next time. It's a best practice to regenerate the mesh after the design strips are modeled so that the mesh aligns with the strips as best possible.
Not in RAM, i ask in Staad Pro Connect Edition,for a person who has model and add slab without generating mesh,what will be the effect of load distribution on beams
Your question:
1. what is the difference between plate load and the floor load ? Should I apply floor load or plate load after generating mesh to the plate ?
Answer:
By plate load, we assume you are referring to the "ELEMENT LOAD" command.
If you have included the slab in the model as a plate element mesh, then, any pressure load or concentrated load acting on the slab should be applied on the model using the ELEMENT LOAD command. Thus, an ELEMENT LOAD can be applied only if there are plate elements.
If you do not use a plate element mesh, but instead, use an alternative method to model the slab like a rigid diaphragm, or the master-slave command, then, the FLOOR LOAD command is a tool to apply the pressure load acting on the slab. The XRANGE, YRANGE and ZRANGE options of that command help the program in identifying the location on the structure where the pressure load acts.
2. Should I apply self weight to the slab (25 x D) KN/M^2 also under dead load of plate pressure / floor load category to the slab also even after giving dead weight (-1) to the whole structure ?
If the slab is included in the model through a finite element mesh, and if the density of concrete has been specified for those elements, the selfweight command will instruct the program to calculate the dead weight of those elements too in addition to those of the line members. In such cases, you should not apply the (25 x D) KN/M^2 as a separate pressure load (assuming that you meant that 25 kN/m3 is the density of concrete and D is the thickness of the slab).
But if you are using the rigid diaphragm or master-slave methods, then you need to use the FLOOR LOAD command to consider the slab weight.
Kris Sathia
I am clear in doubt no 2 which were asked in above tread. However, I am still having doubt in point no 1. Also, I would like to add few more questions. Please help me to clear it.
Doubt 1
In continuation of Doubt 1, Can we add load on plate under (Plate Load - Pressure on Full Plate) after meshing to a plate and without meshing ?
Also, Please help me to know, Is there any tutorial link to use ( Element Load, Master Slave command) or rigid diaphragm to model slab ?
Doubt 3 -
If I am applying a Live load of -10 KN/M2 in GY direction on a plate (casted by plate element cursor), I am not able to see the post processing result. However, If I am using only the dead load(-1) to the whole structure, I am able to see the post processing result (Includes BM, SF, stress diag . etc). Please help me to know what is the reason and how to rectify it.
P.S - I have set scale value as well and turn on all stress icon also.
Doubt 4-
In continuation of Doubt no 3 , If I am applying a Live load on Plate (by Plate Load - Pressure on Full Plate) without meshing , I am also not able to see any value ("0" value is showing) under LIVE LOAD in post processing mode (Also SF, BM diag is not visible).
Doubt 5-
In Output file - concrete design, Stadd is not showing slab design details.
I have also attached project file along with this list of doubt.3632.Structure1.std
The expression "Pressure on full plate" is to be interpreted as pressure on the full area of the element or elements that the load is applied on. Thus, it acts on the full area of all the elements that are mentioned in the element list. So, for example,
1 TO 49 PR GY -2.5
means 2.5 units of pressure acting on the full area of each of the elements 1 to 49.
If you do not mesh the slab and define it as a single element and apply the pressure on it, the load will act on the full area of the slab.
For answering the rest of your questions, I will defer to some of the others.
Please see the screenshot below - the plate load is applied and you can switch the diagram onscreen as shown:
The batch mode element design is available in the Output file - see the screenshot below:
AndrejLogunov
Please address the following query
paresh said:Doubt 4- In continuation of Doubt no 3 , If I am applying a Live load on Plate (by Plate Load - Pressure on Full Plate) without meshing , I am also not able to see any value ("0" value is showing) under LIVE LOAD in post processing mode (Also SF, BM diag is not visible)
In continuation of Doubt no 3 , If I am applying a Live load on Plate (by Plate Load - Pressure on Full Plate) without meshing , I am also not able to see any value ("0" value is showing) under LIVE LOAD in post processing mode (Also SF, BM diag is not visible)
My doubt is - " If I am applying a Live Load on plate element, I am not able to see any BM due to LL on plate and any changes in Beam BM. Please help me to know why is it so ? and what is the possible reason behind this ?
In continuation of above, I have one more question -
How to design reinforcement of slab if we meshed a plate into 'n' no of plates ? Because in this case, every small plate have different value of BM and stresses. Same is the case for beam.
In practical case, slab and beam can't be design for 'n' no of small small elements.
I have also attached modified staad file after meshin
g.2625.Structure1.std
If you do not mesh the slab, any load acting on the slab will bypass the beams and go directly into the column. So, the slab load will not induce any bending in the beams. That slab load will not induce any bending in the slab either. In the stiffness method, the pressure is converted to concentrated forces and concentrated moments at the 4 corners of the slab. For an unmeshed slab, the 4 corners coincide with the top nodes of the columns. So, the entire slab load goes directly as point forces and moments on the columns.
Regarding viewing the applied loads - see below:
Use the programs RAM Concept or RCDC FE for designing the slab.
Use the program STAAD Advanced Concrete Design (also known as RCDC) for designing the beams.
@AndrejLogunov
I have seen many tread, where we can design a slab using " Floor load" also. My question is - " If we're designing a slab using "floor load" (without generating plate), how can we get the output of slab reinforcement details in this case?, because in this case, all the stresses will transfer to the beam directly and further to the column through column and may lead to design of over reinforced beam.
I have run an experiment analysis where I am getting higher reinforcement in beam (say beam no X) (when the structure is designed using Floor Load method instead of plate meshing under same loading condition) ?
Which one method is more accurate Floor load or plate meshing to design ?
I would recommend meshing the slab together with the beams - through the common nodes they will act as monolith. Apply plate loads to the plates and the loading will be distributed to beams below, etc.. If you apply floor load - it will be applied to beams, not plates. Then design beams and plates as mentioned before.