Week 8 Challenge
- Question no 1.
- Ans -
- Files are attached below.
- Aim - To apply load exercise to member of the structure.
- Introduction - Here we can apply self weight, dead load and live load to member of the structure. Also we can apply load combination to the structure. as per given data we applied load to the structure.
- Dead load - a constant load in a structure (such as a bridge, building, or machine) that is due to the weight of the members, the supported structure, and permanent attachments or accessories.
- Live load - Refers to loads that do, or can, change over time, such as people walking around a building (occupancy) or movable objects such as furniture.Live loads are variable as they depend on usage and capacity. However, design codes can provide equivalent loads for various structures.Loads prescribed by codes are empirical and conservative based on experience and accepted practice.IS875 part 2 deals with imposed loads on buildings produced by the intended occupancy or use.
- Load combination - We can apply load combination to the structure by using the IS 800 and IS 1893 code provisions. Load combination is a combined various loads applied to the structure to get its results.
- Given -
- Form a Load case as DL for Dead Load.
- Apply Self weight.
- Apply member load of 3 kN/m on the rafter.
- Apply member load of 6 kN/m on the secondary beams.
- Apply point load of 20 kN at node intersecting inclined member on the top chord.
- Form a Load case as LL for Live Load.
- Apply member load of 4 kN/m on the rafter.
- Apply member load of 7.5 kN/m on the secondary beams.
- Form load combination 1.5DL+1.5LL.
- Process -
- Go to loading option in that load case details.
- Add loads such as dead load, live load.
- In member load put loads as per given data.
- Choose Y direction to apply loads.
- Negative sign acts as a downward direction.
- Assign loads to selected member as per given data.
- For nodal load go to it add load at FY point.
- Assign load to selected nodal points.
- For load combination go to load combination option.
- Select dead load, live load and apply factor as per given data.
- Here we can take as servecibility criteria so add one additional load combination.
- 1DL+1LL.
- After that add load combination.
- Question no 2.
- Ans -
- Aim - To run the analysis and find results on the member mentioned.
- Introduction - We run the analysis and to analyze the maximum force, maximum moment and maximum shear for the members. Run the analysis means there is option in staad pro to run analysis in that we do the perform analysis. After analysis of structure we get the maximum moment, maximum force.
- Maximum moment - It refers to the bending of the beam or any structure upon the action of the arbitrary load. Maximum bending moment in the beam occurs at the point of maximum stress. Also, maximum bending moment will be at the point where shear force changes its sign i.e., zero.
- Maximum force - It is a force in which we take the maximum value of the analysis of member.
- Given -
- Run the analysis.
- Find the Maximum Moment in the Secondary beam for 1.5DL+1.5LL case.
- Find the Maximum Axial force on the inclined bracing and identify the member having the maximum force for 1.5DL+1.5LL case.
- Identify Bottom chord of Truss having Maximum shear Force & Maximum moment for 1.5DL+1.5LL case and present the values.
- Maximum moment for secondary beam 1.5DL+ 1.5LL case - 53.343 KNm.
- Maximum axial force on inclined bracing - 456.949 KN.
- Member on which acts maximum force for 1.5DL+1.5LL case - Beam member no 13.
- Maximum shear force for bottom chord - 260.262 KN.
- Maximum moment for bottom chord - 420.855 KNm.
- Member on which acts maximum shear force and maximum moment for 1.5DL+1.5LL case - Beam member no 1.
- Question no 3.
- Ans -
- Files are attached below.
- Aim - For given staad file in question, to view and rectify the warning, instabilities in the structure. Also fix it and run the analysis.
- Introduction - Here we can find the instabilities in attached file. We run the analysis to get proper results of it.
- Warnings - Sometime in staad at time of run analysis. It gives some errors related to modelled structure. Warnings are nothing but we can do mistake in model or we can not do the proper way to model the structure. Warnings are related to properties, materials, specification and disjointed the model of structure.
- Instabilities - Instability will occur due to not properly model the structure. It is occur due to combinations are not properly defined. so this instability and fix it after analysis has done.
- Process -
- Go to given attachment.
- Open the model of structure.
- After go run analysis option
- Choose perform analysis.
- Run the analysis.
- See the warning in view option.
- See the instability in the Results layout option.
- Choose that and fix it.
- After all warnings fixed we was run the analysis and see the results.
- For warnings join the joint 47 and 48 to fix it.
- After run the analysis we found that threre is instability occurred.
- Go to results view instability for the joint.
- Question no 4.
- Ans -
- Files are attached below.
- Aim - To apply design parameters for modelled structure as per IS 800:2007 code.
- Introduction - Here we can design parameters for the structure. Design parameters are includes effective length, effective length factor, also apply other parameters such as utility factor etc.
- Effective length - Effective length is a critical concept in Structural Design which relates to the length of a component which is effectively restrained. Staad give the option to apply effective length for beams and other element.
- Effective length factor - The effective length factor is obtained by solving the exact equations numerically which require many routine calculations or by using a pair of alignment charts for the two cases of braced frames and sway frames. effective length factor is factor which is obtained by the taking its support condition or effective restrained or unstrained or free the member. Staad also give effective length factor option to design it.
- Process -
- Go to analysis and design.
- Select steel as material.
- Select IS 800:2007 code.
- Define design parameters.
- Apply it on beam and truss element.
- Here we take Lx - not applicable.
- Ly - as a default use for apply to member.
- Lz - as a default use for aaply to member.
- Ky - as factor take 1.2 as per IS 800.
- Kz - as factor take 1.2 as per IS 800.
- Other parameters such beam apply to selected as 1.0.
- Utility ratio as take 1.2 for apply to structure.