A Literature Review of Design Portal Frame

Literature Review

Introduction

The purpose of this literature review is to summarise and analyse key literature content which was relevant in the research process of this project. The review consists of an overview of key topics such as cost, materials, frame & member design and joint behaviour. Assessing and review the topics will assist in selecting the most appropriate design and materials to meet the projects constraints and requirements.

Cost & Materials

A significant number of portal frames used within the construction industry are constructed out of either steel or wood. In recent times wooden portal frame construction has become vastly popular. This may be due to wood offering builders and designers several advantages over common materials such as being a renewable energy source, storing carbon dioxide, manufacturing process requiring less energy and costing less to manufacture vas reducing the cost of the material (WoodSolutions. 2011). Although reports show that wood is a cost effective solution, it cannot be definitively determined unless a case by case scenario is assessed by analysing the application of materials and cost.

Balsa wood has the best strength-to-weight ratio of any other readily available material in today’s market. The material has a wide range of commercial uses because of its insulation properties, it is used for items such as airplane and modern speakers, lining incubators and model airplanes and toys. Kilogram for kilogram balsa wood is stronger than many other materials, it is light weight yet very high in strength (Wengert 2005). The strength of the material varies greatly with its density, due to this testing of the balsa wood will be conducted before the construction of the project. The materials specific bending moments, strength and characteristics will be recorded. Balsa wood also had different grain structures (refer below) A grain Balsa wood has long fibres across the length of the wood, which are the best type for tension members. C grain balsa is preferred for compression members (Garrett Boon 2005).

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Figure 1 – A Grain (Garrett Boon 2005)

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Figure 2 – Crain (Garrett Boon 2005)

Frame and Member Design

There is a vast variety of portal from design used in the construction industry of many different purposes. Some of the various designs are shown below.

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Figure 3 Fame design                                                                         NAFI B. 2009

Due to the design constraints of this project many of the above deigns are not suitable but some are which includes the flat portal from design. Simplicity and ease of construction are required due to the limitation of materials and tools of the team also simple analysis of the frame design is required.