Designing And Analyzing A Modified Warren Truss For Axial Load Analysis

What is the importance of doing this practical? Where might these results be used in reality/practice? 
Include any relevant theory that is necessary for background/completion of the practical. Provide enough background to the reader so that they will know the context and purpose of the experiment.
Provide a brief sentence outlining the aim of the practical. What is the desired outcome?

Factors Considered for Project Selection

A truss describes a structural element made up of a triangulated system of straight interconnected members. The structure is commonly used in buildings to support roofs and in many applications where an internal loading is readily provided as in this project. The modified Warren trusses will be used in this project so that the 5 diagonal members on the 2m long truss could alternatively carry the tension and compression loads, while the members constitution the truss are less than other types of trusses would require.

For this project, the five members will have proving rings incorporated in the truss, to allow the determination of the axial loads. This is achieved because the proving rings can undergo tension or compression in direct linear proportion to the axial loads experienced by each individual member. The axial loads will be accurately determined through the installation of dial gauges in the rings, and thus allowing any slight deflections in the diameter of the rings after the load has been applied at mid-span to be measured. The rings will however require calibration so that the measured values can be converted to units of force. For the members of the truss that are in compression, the ring will be squeezed and the dial gauge will rotate in one direction, while those in tension will stretch their rings and the dial gauges will rotate in the other direction.

In dot points describe the factors you considered for project selection

The project is based on the concepts of solid dynamics where forces are analysed on different elements of the truss, and it will help me to apply my theoretical knowledge of loading and bending moments in the practical.

• The method of the project will entail analysing the tensional and compressive forces on the elements of the truss when a load is mounted mid-span the truss by using proving rings and dial gauges and making it challenging but manageable.
• Since the project is based on the concepts of solid dynamics, it will give me the opportunity to learn and develop skills in loading and bending moments analysis which are a requirement in any structural projects, a field of engineering I am passionate about.
• The results of my project will highlight the different trends in axial loading, bending moments, as well as the tensional and compressive characteristics of the members of the plane truss I designed, allowing me to make recommendations and conclusions that can be implemented on structural plane truss designs that could be utilized in the future.

How many hours you plan to spend on the project weekly?

I will spend 6-12 hours weekly working on this project.

This article offers its readers a theoretical approach in analysing the impact of gravity, especially on a topological scale, on the impact of all dynamic and axial loads exerted on the plane truss. It highlights in theory how possible it is for a simply supported plane truss to support bending, tensile and compressive loads when a small weight is applied in the truss. In turn, it highlights all of the design considerations that need to be factored in for the truss to be able to carry its own weight and that of the applied weight, since it is only supported at its ends. This article added to my design knowledge by allowing me to factor in the impact of gravity on the individual members of the plane truss, and thus helping achieve the overall design of the truss.

This article considered the impact of the elasticity of the materials used for the design of simply supported plane trusses, especially when they are subjected to dynamic and applied loads. It gave a good account of the effect of the elements of the truss and even went ahead to develop an algorithm for this impact. The article was resourceful in highlighting how the minimization of the structural weight of the truss will help to improve the displacements noted on the proving rings, the stress factors the members of the truss will undergo, as well as the optimal sizes of the truss members. It also gives worked examples of how the design parameters can be identified. This resource added to my knowledge by showing me how these factors influence the success of the given design, and even provided worked examples to show why the said factors are expected to affect the design.

Weekly Hours Plan

This article analysed the properties of steel with regard to its applications in the design of trusses, as the material has continually gained increasing popularity as the material of choice for the design of trusses. The material as used in this study performed exceptionally well in highlighting the behaviour of trusses on the elements that experienced tensile forces. It also performed considerably well on the cross sectional area of the truss expected to experience compressional forces but the difference was notable. It also recommended the use of shear connectors at the joints, for the purposes of allowing the beam slabs to function in unison, and to also restrict longitudinal uplifting and slipping of the truss elements. The insights provided in this research help me to design the project adequately for all the results to be collected as expected.

(Moon & Li, 1990) discuss the principles of solid dynamics with regard to the jointing of the individual elements that make up the truss structure. The authors utilized an experimental approach to indicate that when the truss experiences an additional load, the joints experienced vibrations that took a sinusoidal pattern. The authors indicated that these vibrations are as a result of nonlinearities in the joints where two individual members of the truss meet, and an additional load on these joints thus causes excitations and vibrations. Addition of supports like cables is seen to improve the vibrations. This article was resourceful as it helped me to know the best joints for the members of the truss, helping to make it stable and to design effectively for the truss.

This article presented a detailed algorithm on how to optimize the geometric and topological factors of a plane truss supported at the ends and has a provision for applied loads. By considering a uniform cross sectional area of the plane truss being designed in the project, the impact of gravity on both a geometrical and topological scale is factored in and the design is simplified and optimized. It also allows for the individual members to remain at an all-time minimum, reducing the cost incurred in the design and reducing the number of nodes in the truss. This specific article was resourceful in guiding the consideration of the impact of gravity, considering the truss is simply supported at the edges and that it has a provision for applying loads.

(Pao & Sun, 2003) utilizes the reverberation ray matrix method to analyse the axial, shear, and bending loads felt by the individual members in a truss with fixed or pinned joints when an external force is applied on the truss. The results are compared to the results collected when the applied force is applied to a plane truss which joints are fixed and a comparative analysis is conducted. The article was insightful as it helped me to know all the factors to consider in the design of this project, its limitations as well as what can be done to achieve reliable results while conducting this analysis.

(Sangeetha & Senthil, 2017) analysed the individual impact of the different elements on the truss, as well as how the composite truss can transfer all the axial and bending loads to the supports at the ends of the truss. This article helped me to put into perspective the impact of the applied loads as felt on the supports, helping to adequately design the supports for the weight of the truss itself and that of the additional weight expected to be applied on the truss.

Relevant Theory

(Wallach & Gibson, 2001) analyses the structural and mechanical properties of materials used in the design of plane trusses. The structural demands of the truss makes the properties of the materials used in their design an important factor to consider when designing the structure, to ensure the design is effective and successful for the intent it was designed for. For instance, the materials utilized for the design of the plane truss that is simply supported at its ends and has a provision for an applied load requires a relatively stiff and a high elastic modulus. The article was resourceful as it helped me put into perspective the impact of the structural properties of the material chosen to the shear and uniaxial strengths that the material will have and its impact on the stability of the plane truss.

(Wang, Zhang & Liang, 2002) discusses a method of how trusses can be constructed in an optimal manner, so as to minimize the effect of the individual members of the truss. The effect of this will be a reduction on the displacement felt by the proving rings and dial gauges of the individual members and thus the axial loads on the truss will be more accurately determined. Any simply supported plane truss is subject to displacement constraints especially after the impact of the added load and minimizing the individual loads will assure more accurate dial gauge deflections when the load is applied mid-span of the truss. This article was helpful in this project as it enlightened me on the best truss design to ensure that the tensional and compressive effect of the added load is accurately reflected on the members of the truss, allowing for results collected in the project to be precise and accurate.

This article clearly highlights the effect the resultant combinations of bending loads and shear loads from the sandwiching effect between the cores of the truss from the plane members of the truss. The source was helpful in the realization of all the axial and bending loads that have to be considered in the design of a simply supported plane truss, making it extremely resourceful.

This article discussed bending tests conducted on a wooden simply supported truss with 42 individual members that also had a provision for an applied load. The study analysed the effects of the modulus of elasticity of lumber and the slope of the truss elements, on the stiffness and the strength of the truss for its designed purpose. The study indicated that the trusses indicated a directly linear proportion of the load applied to the deformation experience in the trusses to different levels depending on the quality of the materials used in the design of the trusses. It was resourceful in exhibiting the expected results of my project and why the truss responded the way it did when the load was applied.

Chiras, S., Mumm, D. R., Evans, A. G., Wicks, N., Hutchinson, J. W., Dharmasena, K., & Fichter, S. (2002). The structural performance of near-optimized truss core panels. International Journal of Solids and Structures, 39(15), 4093-4115.

Feng, T. T., Arora, J. S., & Haug, E. J. (1977). Optimal structural design under dynamic loads. International Journal for Numerical Methods in Engineering, 11(1), 39-52.

Kumar, P. T., Reddy, L. S., Kumar, P. T., & Reddy, L. S. Experimental Studies on Steel-Concrete Composite Beams in Bending. International Journal, 2, 28-35.

Moon, F. C., & Li, G. X. (1990). Experimental study of chaotic vibrations in a pin-jointed space truss structure. AIAA journal, 28(5), 915-921.

Ohsaki, M. (1998). Simultaneous optimization of topology and geometry of a regular plane truss. Computers & structures, 66(1), 69-77.

Pao, Y. H., & Sun, G. (2003). Dynamic bending strains in planar trusses with pinned or rigid joints. Journal of engineering mechanics, 129(3), 324-332.

Sangeetha, P., & Senthil, R. (2017). A study on ultimate behaviour of composite space truss. KSCE Journal of Civil Engineering, 21(3), 950-954.

Wallach, J. C., & Gibson, L. J. (2001). Mechanical behavior of a three-dimensional truss material. International Journal of Solids and Structures, 38(40), 7181-7196.

Wang, D., Zhang, W. H., & Jiang, J. S. (2002). Truss shape optimization with multiple displacement constraints. Computer methods in applied mechanics and engineering, 191(33), 3597-3612.

Wicks, N., & Hutchinson, J. W. (2001). Optimal truss plates. International Journal of Solids and Structures, 38(30), 5165-5183.

Wolfe, R. W., Percival, D. H., & Moody, R. C. (1986). Strength and stiffness of light-frame sloped trusses (No. 04; USDA, FOLLETO 157.). US Department of Agriculture, Forest Service, Forest Products Laboratory.