Australian Standard – Commentary. AEES member and past president John Wilson has produced a publication titled “AS Summary This paper provides a short guide and worked examples illustrating the use of AS Structural design actions Part 4. Download AS _Earthquake Actions in Australia_pdf.
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Worked examples To illustrate the use of the Standard, following are some examples of the design required for various site conditions. One of the fundamental principles of this approach is the removal of hidden factors through the provision of an umbrella document that defines the loading and resistance levels for ass using the design event approach. Determining the period of an existing structure, however, is a simple exercise involving measuring its vibrations.
This requires the structure and indeed the whole building to be able to deform with the earthquake and absorb energy without vertical supports giving way. Therefore, it is not expected that a structure subject to the design earthquake would be undamaged, but rather that the damage had not progressed to collapse.
Therefore, the materials design Standards are much simpler than those required in high hazard areas. Section 6 sets out the method including the spectral shape factor, the structural ductility and performance factors, the natural period of vibration of the structure, etc.
It is calculated by a simple equation given in Section 6 of the Standard. In cases where a static or dynamic analysis is required, the first mode natural period of vibration of the structure is calculated T1. Calculating the base shear For the vast majority of structures low height, normal importance on firm or shallow soils the next step is to 11770.4 if the load is likely to be less than the wind load. For dynamic analysis, the effects of a number of periods of vibration may be summed to determine the action effects in the members 1170.44, therefore, a number of spectral shape factors may be used in the analysis.
Once the horizontal design action is calculated from the above information and the seismic weight of the structure, analysis can be carried out.
The analysis and materials design is where AS Also, as a result of the lower earthquake loads expected, the detailing required is minimal compared to that for such countries as New Zealand. The use of annual probabilities in the examples is based on recommendations to be proposed for adoption in the BCA at the time of adoption of the new Standard: Mu the Greek letter represents the structural ductility while Sp, the structural performance factor, is an adjustment made to calibrate the known performance of structure types to the calculated ductility.
Earlier this year CSIR General principles provides the link between the limit states actions imposed on the structure and the design of materials for resistance. Walls will usually require a check of the resistance to face loading.
AS _Earthquake Actions in Australia_pdf – Free Download PDF
The base shear may be understood to be the percentage of the weight of the building to be applied laterally eg. The site hazard is determined from Section 3 of the Standard.
This approach arises from the small knowledge we have of earthquake risk in Australia coupled with the very low levels of earthquake risk we do currently expect. The key to understanding AS A similar approach to reducing loads assuming 1170.4 higher Mu value could be used where Z is high. The basic aim is to state the design event in terms of the annual probability of the action being exceeded.
AS 1170.4_Earthquake Actions in Australia_2007.pdf
Once the value of Mu is 1170. the structure must then be detailed to achieve that selected ductility. Selecting the analysis method Once the annual probability of exceedance, the hazard value for the site, the sub-soil conditions and the building height are known, the required design effort can be determined using Table 2.
Quick paths to an exit If you are designing one of the following structures, you can exit quickly to a simplified solution or even out of the Earthquake Standard altogether: Inter-storey drifts should be checked to ensure that parts such as stiff a do not interfere with the seismic force resisting system.
The method of calculation given is the most reliable method available other than carrying out a full dynamic analysis and even then there are inherent modeling inaccuracies. Generally, for short structures that are not of high importance, simply 1107.4 whether the structure sits on rock or in soils of some depth eg.
In the event that a structure is subject to an earthquake, the ductility provided greatly improves aw performance, regardless of the actual magnitude of the earthquake and the actual design actions. For the lowest values i. The material in which the structure is laterally coupled to the ground provides the site class.
As with all the parts of the series, Part 0 provides the annual probabilities of exceedance or, for buildings covered by the BCA, refers the user to those provided in the BCA. The loads on the structure are then calculated based on this value.
Australian Standards AS Seismic Performance of Engineering Systems
Permanent, imposed and other actions Part 2: The soil type is determined by a geotechnical investigation for taller longer period structures. Many structures do not require this level of design effort as there are conditions for which no further work is required by the Standard.
Earthquake actions in Australia. The ductility is achieved by applying the detailing provided in the materials design Standards currently in use.