Week 9 Challenge
- Question no 1 -
- Ans -
- Files and snaps are attached below.
- Aim - To design dual slope pitched roof frame.
- Introduction - Here we can design the roof frame as per given data and given figures. Also Pitched roof frame is frame which slopes are downward in two parts.
- Pitched roof frame - A pitched roof is a roof that slopes downwards, typically in two parts at an angle from a central ridge, but sometimes in one part, from one edge to another. The ‘pitch’ of a roof is its vertical rise divided by its horizontal span and is a measure of its steepness. From the beginning of civilization, roofs are one of the essential structural components, necessary for building construction.Roofs protect the building structure and the inhabitants from adverse atmospheric and exposure condition and also to enable privacy to its inhabitants.
- Types of Pitched Roof
- Depending upon the slope, environmental condition, aesthetic view, and number of sloping surfaces, the pitched roof are widely categorized into the following types
- Mono-Pitch Roof.
- Double-Pitch Roof.
- Couple Roof.
- Couple Close Roof.
- Collar Beam Roof.
- Slant Roof.
- Purlin Roof.
- King Post Roof.
- Given -
- A 3 hinged pitched roof frame.
- Assumed no wind load acting on the walls and roof of frame.
- Analyse the frame structure and draw bending moment, shear force and axial force diagrams of the frame.
- The slope of the roof = 1 in 10.
- The roof is accessible for maintenance purpose (assume 75 kg/m^2) only.
- Dead load on the roof are given below.
- Bay spacing = 5 m.
- Frame width = 20 m.
- Design code = AISC:ASD.
- No seismic load consideration.
- Weight of roofing sheet = 5 kg/m^2.
- Weight of purlins + tertiary members = 25 kg/m^2.
- Weight of roofing sheet = 5 x 20 = 100 Kg/m = 0.98 KN/m.
- Weight of purlins + tertiary members = 25 x 20 = 500 Kg/m = 4.90 KN/m.
- Roof for maintennace purpose = 75 x 20 = 1500 Kg/m = 14.71 KN/m.
- Process -
- Open the staad.
- Create the model of structure file and open it.
- Define and assign the nodes and beams ap per given data of structure.
- Assign properties of structure such as tapered section and beta angle for columns.
- Create and assign the support to columns and at internal hinge.
- Add loading such as load case details as per given for dead load and Live live.
- Add load combination such as DL + LL.
- In loading we assign self weigth, member load as per given data.
- Go to analysis and perform analysis.
- After that go to design use AISC:ASD code in options.
- Add design parametrs and apply on the structure.
- In commands use steel take off and check codes, apply on structure.
- Check utility ratio is less than 1 or not.
- Do some try error based properties after we get proper section which uitility ratio less than 1.
- Seen the bending moment diagram, shear force diagram, axial force diagram.
- Also seen the maximum bending moment, maximum shear force, maximum axial force.
- Check our section is pass or fail in design.
- Question no 2.
- Ans -
- Files and snaps are attached below.
- Aim - To draw bending moment diagrams of given frames.
- Introduction - Here we draw the bending moment diagram as per given frames and its loadings. Here we use staad software to draw bending moment diagram.
- Bending moment - A bending moment (BM) is a measure of the bending effect that can occur when an external force (or moment) is applied to a structural element. This concept is important in structural engineering as it is can be used to calculate where, and how much bending may occur when forces are applied. The most common structural element that is subject to bending moments is the beam, which may bend when loaded at any point along its length. Failure can occur due to bending when the tensile stress exerted by a force is equivalent to or greater than the ultimate strength (or yield stress) of the element. However, although the mechanisms are different, a beam may fail due to shear forces before failure in bending.
- Bending moment diagram - It is a diagram in which the deflection or bending of beam or column is takes place in to account for certain loading condition. Drawing of bending moment diagram for frames as perfix, hinge and pineed support conditions.
- Given -
- Figure 1 -
- Supports are fixed and pinned.
- Angle of slope = 5.71 degree.
- Width of frame = 20 m.
- Height of end column = 10 m.
- Height of mid column = 10 tan 5.71 = 0.99 = 1 m.
- Height of mid column = 10 + 1 = 11 m.
- Loading = udl = 20 KN/m.
- Point load = 10 KN.
- Process -
- Create frame model on staad.
- Assign properties as to beams and columns.
- Assign loading to section of member.
- Run the analysis.
- Check bending moment diagram.
- Figure 2 -
- Supports are pinned.
- Angle of slope = 20 degree.
- Width of frame = 10 m.
- Height of end column 1 = 20 m.
- Height of end column 2 = 10 tan 20 = 3.64 m.
- Height of end column 2 = 20 - 3.64 = 16.36 m.
- Loading = udl = 10 KN/m.
- Point load = 30 KN.
- Process -
- Create frame model on staad.
- Assign properties as to beams and columns.
- Assign loading to section of member.
- Run the analysis.
- Check bending moment diagram.
- Figure 3 -
- Supports are hinged.
- Width of frame = 8 m.
- Height of end column = 10 m.
- Loading = udl = 20 KN/m.
- Point load = 10 KN.
- Process -
- Create frame model on staad.
- Assign properties as to beams and columns.
- Assign loading to section of member.
- Run the analysis.
- Check bending moment diagram.
- Question no 3.
- Ans -
- Files and snaps are attached below.
- Aim - To Find lateral and vertical deflection at points.
- Introduction - Here we can find the lateral deflection on previous results for points A. We can find vertical deflection on previous results for points between AB, BC, B.
- Lateral deflection - Lateral deflection is movement perpendicular to the axial plane of the expansion joint. It is a shear motion on the belows. Lateral deflection involves positioning the flowline end to one side of the target structure and then pulling it laterally into position.
- Vertical deflection - The deflection of the vertical is the difference in direction between the direction of Earth's gravity vector and some reference direction, such as the direction perpendicular to a given reference ellipsoid or the direction of some reference gravity field (the normal gravity). The vertical deflection (VD) or deflection of the vertical (DoV), also known as deflection of the plumb line and astro-geodetic deflection, is a measure of how far the gravity direction at a given point of interest is rotated by local mass anomalies such as nearby mountains. They are widely used in geodesy, for surveying networks and for geophysical purposes.
- Process -
- Create frame model on staad.
- Assign properties as to beams and columns.
- Assign loading to section of member.
- Run the analysis.
- Check Deflection.
- Go to deflection option check it.
- For lateral deflection we take horizontal X.
- For vertical deflection we take Vertical Y.
- For choosing value of deflection we take maximum value.
- For Figure 1 -
- Lateral deflection at point A = 4.34 mm.
- Vertical deflection at mid section between points B and C = 185.955 mm.
- For Figure 2 -
- Lateral deflection at point A = 8886 mm.
- Vertical deflection at mid section between points A and B = 380.643 mm.
- For Figure 3 -
- Lateral deflection at point A = 19.921 mm.
- Lateral deflection at point B = 19.918 mm.