Summary
We have designed a truss to support a point load, placed at 190mm from the edge of a 450mm gap. The vertical face of the trusses is modelled on the already established ‘K’ truss design, but the overall shape of the structure is our own. There are three ‘K’ units on each truss. The two vertical faces are held together at the top by another truss-like design. We modelled this on the ‘N’ truss.
The truss is constructed from hot-dog sticks, glue and bolts.
Introduction
The task was to construct a truss out of 48 hot-dog sticks and 30 bolts to support as large a point load as possible. It was to span a gap of 450mm and to support a load placed at 190mm from the end. The truss may have a maximum depth beneath the supports of 130mm, and the loading rod placed not more than 110mm beneath the supports. Member ends must be bolted and the forces within the members calculable.
Project Objectives
• Maximise the load capacity of the truss
• Achieve an even distribution of force to each member
• Construct the truss carefully for maximum quality
• Design a truss which did not fail from flexural-torsional buckling.
Development of the Model
We began by researching established truss designs, such as the Bailey bridge, Baltimore bridge and the N truss. We realised that although each type of truss was useful for its own purpose, none of the bridges was intended for supporting a point load. However, we compared the designs by calculating the distribution of forces in the members. This gave some guidance to the development of the model.
We researched the ‘K’ truss, which is composed of many repeated ‘K’ units, in either direction. This design gives the most even distribution of force to the members, which satisfies o...
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... to the members; reinforcing material glued to compression members; holes drilled towards the middle of tension members to give extra support; the rounded shape of the top and bottom of the trusses for improved weight distribution; and the ‘N’ truss design on the top and bottom to prevent flexural-torsional buckling.
Drawings are over the page
Conclusions
• The K-truss is the most effective means of distributing a point load amongst members, under determinate conditions.
• Increasing the concavity/ angle of the outer members of the truss lessens the forces in the members.
• Reversing the direction of the K’s at the position of the point load helps to lessen the force in the corresponding vertical members.
• It is desirable to have as many K’s in the truss as possible. The solution is maximised so that all 30 bolts are used, giving a good amount of K joints.
...Modelling: Rigging Patterns - The Carracks and Caravels." Jan's Sites: Navigation. N.p., 8 Mar. 2012. Web. 24 Nov. 2013.
A connecting rod subjected to an axial load F may buckle with x-axis as neutral axis in the plane of motion of the connecting rod, {or} y-axis is a neutral axis. The connecting rod is considered like both ends hinged for buckling about x axis and both ends fixed for buckling about y-axis. A connecting rod should be equally strong in buckling about either axis [8].
According to Suspension bridges: Concepts and various innovative techniques of structural evaluation, “During the past 200 years, suspension bridges have been at the forefront in all aspects of structural engineering” (“Suspension”). This statement shows that suspension bridges have been used for over 200 years, and that people are still using them today because they are structurally better bridges. This paper shows four arguments on the advantages of suspension bridges, and why you should use one when building a bridge. When deciding on building a suspension bridge, it has many advantages such as; its lightness, ability to span over a long distance, easy construction, cost effective, easy to maintain, less risk
The swinging arm is a 40 cm long plank that is attached through a metal rod. The uprights in the frame have 5 cm of wood showing above the triangle posts so that a 10 cm metal rod can fit in between them, creating an axel bar. The swinging arm is attached to this rod because there will be a hole in the arm 2 cm from the end, used to slide the arm through the metal rod. (Kalif) The hole should be big enough to allow the swinging arm to move around comfortably, but not too loose. A picture of the swinging arm and metal rod is shown in the photo
counterweight is hoisted up as high as possible it has lots and lots of potential
One of the most influential engineering discoveries in the past century was the ill-fated Tacoma Narrows Bridge. “Galloping Gertie” as she was known to local residents, the massive Washington state suspension bridge shook, rattled and rolled its way into the history books. Legendary in its time, the Tacoma Narrows Bridge held many records and drew tourists from around the world in its short life. However, the famous bridge is not known for its creative engineering or speedy construction, unfortunately the bridge was destined to fail. That failure in turn changed the way every building is constructed today as well as further man’s understanding of physics and the forces of nature. In this paper we will examine the history of the Tacoma Narrows Bridge from design to construction, the failure of the bridge, and ultimately the rebuilding project.
The structural torsional stiffness is calculated through finding the torque applied to the handle and dividing it by the angular deflection of the handle that is resulted from the torsional loading. It is expressed in term of Nm/degree of angular deflection. This calculation is shown below in figure 3.1
Laws such as the lever law and Euler’s Buckling Theorem come into play when testing and competition begins. A structure of wood and glue surely has much more to offer than meets the eye.
This design employs an enhanced low-impact design, with an estimated weight load of 220 lbs.
Mechanical Engineering 130.2 (2008): 6 - 7. Academic Search Complete. Web. The Web. The Web.
Bridge efficiency is important as it helps reduce cost of building while maximizing the strength of the bridge. Many things can influence the bridge’s strength and weight, but the two main things that can cause a bridge to be a failure or success is the design of the bridge and construction of its joints. In order to build a potent balsa truss bridge, it is crucial to know how the layout of members and style of gluing can help increase or decrease strength.
== = Inside the structures I will be investigating the joints I predict to find are the following: --------------------------------------------------------------------- three joint-3J four joint-4J five joint-5J six joint-6J [IMAGE] [IMAGE] [IMAGE] [IMAGE] Found on the Found on the Found on the Found inside vertices edges faces I will now investigate the joints above and any others I find in cubes and cuboids. Joints
Load cells are also available in Quarter Bridge configuration i.e. consisting of a single strain gauge or half bridge configuration of 2 strain gauges.
Fanella, D. (2011). Reinforced concrete structures: analysis and design / David A. Fanella. New York: McGraw-Hill, c2011.
...aft for six feet stretched 2006 Hummer H2. I had to design the shaft for critical speed and its torsional strength by taking into consideration for minimal vibrations in operation at different engine speeds. I’m thankful to my Manager Mr. Ayaz Patel for believing in me and giving an opportunity to demonstrate my skills.