JOB NO# 1 Plotting of Maxwell Diagram Theory, Instruction, Experiment and Comments Objective: It is the graphical method to represent a truss.
Related Theory: Maxwell Diagram: It is a method of graphical analysis of external forces within a truss it is a composite diagram which combine into one, all the separate forces polygons for the individual joints of a truss. Types of Truss: There are different types of Maxwell Diagram as shown below. Howe Truss:The relatively rare Howe truss, patented in 1840 by Massachusetts millwright William Howe, includes vertical members and diagonals that slope up towards the center, the opposite of the Pratt truss. In contrast to the Pratt Truss, the diagonal web members are in compression and the vertical web members are in tension.
Pratt Truss:-
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A Pratt truss includes vertical members and diagonals that slope down towards the center, the opposite of the Howe truss. The interior diagonals are under tension under balanced loading and vertical elements under compression. If pure tension elements are used in the diagonals (such as eye bars) then crossing elements may be needed near the center to accept concentrated live loads as they traverse the span
Bowstring K Truss:bowstring trusses not created equal and do not share the same characteristics when found in a
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They may have the same shape, but shape alone does not define the bowstring truss. Based on the type, design, construction, materials, age, span, spacing, configuration, occupancy and application there are vast differences AND similarities.
Bowstring Truss:The bowstring truss bridge similar in appearance to a Tied-arch bridge, a bowstring truss is a truss and thus has diagonal load-bearing members. These diagonals result in a structure that more closely matches a Parker truss or Pratt truss than a true arch
Fink Truss:A symmetrical truss, esp. used in supporting large sloping roofs; in the form of three isosceles triangles one in the center with its base along the horizontal tie, and each of the outer two having its base along the sloping sides of an upper chord.
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K-Truss:A truss in the form of a K due to the orientation of the vertical member and two oblique members in each panel.
Warren Truss:The Warren truss consists of longitudinal members joined only by angled cross-members, forming alternately inverted equilateral triangle-shaped spaces along its length, ensuring that no individual strut, beam, or tie is subject to bending or torsion straining forces, but only to tension or compression.
Belgian Truss:Similar to a W truss or a Warren truss for longer spans with extra webs added. Also called a double Fink truss. A symmetrical truss, esp. used in supporting large sloping roofs; in the form of three isosceles triangles one in the center with its base along the horizontal tie, and each of the outer two having its base along the sloping sides of an upper chord.
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X-Truss:Stable and reliable, easy in handling this is why experts in booth building and stage design. Truss is precisely coordinated and can be combined with each other. Truss is precisely coordinated and can be combined with each other design.
Scissor Truss:A scissors truss is a kind of truss used primarily in buildings, in which the bottom chord members cross each other, connecting to the angled top chords at a point intermediate on the top chords' length, creating an appearance similar to an opened pair of scissors. Scissors trusses are used almost entirely in building construction to support a pitched roof, where a sloping or raised ceiling surface is desired.
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Steps of Maxwell Diagram: Graphical method is very helpful to find out unknown forces It consist of the following steps i. ii. iii. iv. v.
vi.
vii. viii.
Find external reaction of the supports Sketch truss according to scale and applied external loads Give proper numbering to joint and also number the rigid enclosed to external forces and also enclosed by truss elements Select an appropriate scale and draw externally applying load according to scale and also draw the support reactions to enclosed the force polygon Select a joint at which number of unknown forces will be less than three and sketches the member forces to through the respective points and the intersection of line of action of member forces will produced a new point corresponding to a specific region the length of a lines will gives us the magnitude of forces for the member connected at that joint Move to next joint for which number of unknown forces less than three and repeat the same procedure. Continue this process until all joints completed and length of each line will give the magnitude of the force in that member. To determine the sense of the force (tension and compression) select the single joint and mark the region collected at that joint in clockwise direction. The direction assessed by the arrangement of region in clockwise will indicate the direction of forces in the corresponding member and of member force in a way from joint then it indicate that member under tension and if the direction in towards the joint if shows that member under compression.
Advantages of Maxwell diagram: ix. x. xi. xii.
In this method we can find the magnitude of force in different members Tensional and Compression members are shown This method is free from calculations. It is useful to find out unknown forces
Comments xiii. xiv. xv.
I am able to draw the graph of forces of truss I am able to know about tension and compression member I am able to know the stable truss
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