Executive summary
In the construction of industrial establishments, the use of truss frames is a common practice. A factor that informs the use of steel elements in these structures is the fact that they allow for construction to be conducted swiftly while offering the required stiffness. This report indicates how new steel frames can be developed, informed by the realization that the previously used timber truss have deteriorated in quality. The predictions that old structures cannot withstand increasing wind loads also inform the new designs.
In this report, the loads on the frames have been established to shed light on the limits of the alterations that can be made on the frames. The loads have been determined using the information that the client has offered primarily regarding the dead load and wind load occurrences in different cardinal directions. Besides, the report shows the calculation of bending moments, shears, and axial forces. This calculation has been aided by a computer analysis model program; Space Gass. Considering the stiffness of different members and the designed increase of loads, a non-linear analysis of the model has been accomplished. The design team, informed by individual engineering experience and judgments has engaged in various design force calculations to verify the model.
Top Chord 205 BT 26.9
Bottom Chord 180 BT 25.4
Internal Web Members 100 x 12 EA
Vertical Chord 150 UB 18.0
The Australian Steel Institute (ASI) capacity tables were used to analyze each of the four members mentioned above. Besides, the design team was responsible for making a choice between either bolted connections or welded connections. The analysis revealed that the welded connections were best, by virtue of being easy to construct. The welded connections were, therefore, used, with the weld; a 4 mm General Purpose fillet with a minimum length of 100 mm used. The minimum length was employed to accommodate the possible welding errors.
It is important to note that the design team found out a difference between the manual calculations done on the bottom cord and the report from the Space Gass program. According to the manual calculations, the cord was intended to be an 180 BT 25.4, while Space Gass required it to be an 180 BT 28. Considering that the difference in the two figures was small, its effect on the integrity of the element was negligible. Guided by their engineering judgments, members of the team decided to proceed with the member, since it was seen as able to serve its purpose.
Introduction
Frames are structures that are mostly used for industrial construction processes as opposed to being used in other forms of construction. Overall, these frames are useful in serving the purposes of industrial constructions. This is in regard to offering the required strength and stiffness by use of the very light material. Another important aspect of using frames for industrial purposes is that they provide large spans which are easily constructed at a relatively low price. By virtue of their poor aesthetic quality, truss frames are not commonly used in other forms of construction apart from industrial ones. Their ease of their use and the virtue of being cheap to make these frames a perfect fit for industrial purposes.
Purpose of report
This report is compelled by the need to replace timber reinforcement in an industrial setting. The report looks into the factors that come into play when making the decision to replace timber truss, which is a standard material in industrial construction. The report establishes that the wood truss is being replaced since the quality of the timber is compromised. The poor quality of timber is expected to be insufficient in supporting an increase in loading. The report also establishes that there is an expected 15% increase in the level of wind loads. The implication is that a stronger system made of steel is required.
The purpose of the report will be to come up with the precise measurements regarding the loads on the truss. These measurements will be calculated with the new wind loads in mind. The goal here is to establish the critical aspects within the truss. This process will make it possible for an informed structural analysis to be conducted. This analysis will be informed by the previously established critical members and the calculated maximum loads.
Background
The changes in global climate patterns have a considerable impact on various aspects of the world. The Department of Climate Change and Energy Efficiency (2012), notes that the changes in climate have influenced both natural and human systems globally. The implication is that the world needs to come up with creative ways of coping with these changes. An important aspect of these climatic changes is the variation of wind loads in Australia and the rest of the world. In a bid to cope with changes in wind patterns, it is advisable for the Australian Wind Action Code (AS/NZS 1170.2) to be reviewed. This review should take care of the increased wind loads and ensure that Australia is well prepared for the changes (Department of Climate Change and Energy Efficiency, 2012). In this particular case, the client shares this concern of wooden truss jot being able to withstand the changes in wind loads. The customer has made an observation that the design and structure of the wooden truss are compromised, meaning that the structure can no longer serve its purpose, especially when increased wind loads are considered.
Scope
Given the expected climatic changes in Australia, it is estimated that the structure of old industrial buildings will not be sufficient. This is because the condition of truss members in these old structures has become worse, meaning that they cannot adequately serve their purpose. In a bid to overcome this problem, this report looks into how old industrial structures can replace deteriorating truss members with open channel hot rolled steel members. This report, therefore, conducts an extensive 2D analysis of a non-linear frame critical members. Specific aspects defining the key members will be emphasized on, and these include axial tension, shear and bending.
This examination will have the goal of establishing whether the member serves their purpose in different load scenarios. In constructing the frame, four sections will be independently handled. First is the top chord, followed by the bottom chord, the internal web members and finally the vertical chord. An important aspect of the analysis will be the connections since they are essential in coming up with a complete frame design to be presented to the customer. There are, however, some aspects that are beyond the scope of this report, and these include connecting beams and columns. Analysis of these components will not be conducted. In conducting every form of analysis on different elements, a verification procedure of the Space Gass model will be employed. Here, both qualitative and quantitative investigation modalities will be used to ensure that the output from the analyses is accurate. All this will be done facilitated by analysts with experience in engineering and calculations.
