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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In cases where a static or 11770.4 analysis is required, the first mode natural period of vibration of the structure is calculated T1. The examples assume that at least a static analysis has been selected, and therefore, sets out the aw required to calculate the base shear. The value of Z can be read from a Table or, for locations away from major centres of population, determined from the maps.
If they do, the structure will not exhibit the ductility required of it and will therefore attract a much higher load than that for which it is designed.
The Table 11770.4 shows how for many structures, there are points at which no further work is required. This approach arises from the small knowledge we have of earthquake risk in 11700.4 coupled with the very low levels of earthquake risk we do currently expect. Summary This paper provides a short guide and worked examples illustrating the use of AS 11700.4 Inter-storey drifts should be checked to ensure that parts such as stiff walls do not interfere with the seismic force resisting system.
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. Period of vibration of the structure The construction material, type of structure, and 1170.44 period of the first mode of vibration all have an influence on the forces experienced by the structure.
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.
Earthquake actions in Australia.
Process of designing for earthquake actions Earthquake actions are determined by considering the site 11700.4 and the type and configuration of the structure. Detailing rules to achieve these levels of ductility can be highly complex.
For the lowest values i. For Australian conditions, where we have scant knowledge of the earthquake activity, we design for a lateral equivalent static load, unless the structure is particularly vulnerable to dynamic effects.
A similar approach to reducing loads assuming a higher Mu value could be used where Z is high. Analysis of the structure is not covered. The analysis and materials design is where AS Spectral shape factor site hazard spectrum The period is then used to determine the spectral shape factor Ch T1 for the building on the site. In the event that a structure is subject to an earthquake, the ductility provided greatly improves its performance, regardless of the actual magnitude of the earthquake and the actual design actions.
General principles Part 1: The loads on the structure are then calculated based on this value. The Standard also provides the means 110.4 reducing earthquake loads on a structure by achieving zs levels of ductility.
In order to achieve the ductility assumed zs design of the structure, it is essential that stiff elements should not impose themselves on the behavior of the seismic force resisting system.
AS _Earthquake Actions in Australia_pdf – Free Download PDF
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: This was a group of loading ae from across the APEC region that met to create a means of establishing inter-changeability between the loading codes of different nations. The method of calculation given 110.4 the most reliable method available other than carrying out a full dynamic analysis and even then there are inherent modeling inaccuracies.
Once the value of Mu is selected the structure must then be detailed to achieve that selected ductility. This paper assumes that at least a static analysis has been selected, and therefore, the remaining data required to calculate the base shear has to be determined.
Wind actions Part 3: 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. This is required for the highest hazard levels and tallest 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.
The key to understanding AS The ductility is achieved by applying the detailing provided in the materials design Standards currently in use. This value is 1170.44 multiplied by the probability factor kp to determine the site hazard value kpZ for the appropriate annual probability of exceedance. For dynamic analysis, the effects of a number of periods of vibration may be summed to determine the action effects in the members and, therefore, a number of spectral shape factors may be used in the analysis.
This will result in more effort in detailing to achieve the higher Mu assumed.
AS 1170.4_Earthquake Actions in Australia_2007.pdf
General principles provides the link between the limit states actions imposed on the structure and the design of materials for resistance. The soil type is determined by 1710.4 geotechnical investigation for taller longer period structures. The Australian Standard provides for simplified analysis methods based on the low level of hazard. The basic aim is to state the design event in terms of the annual probability of the action being exceeded.
Worked examples To illustrate the use of the Standard, following are some examples of the design required for various site conditions. The 1170.44 is then defined for any annual probability of exceedance so that the design event is independent of the technical definition of the loads.
Therefore, it is not expected that a structure subject to 11170.4 design earthquake would be undamaged, but rather that the damage had not progressed to collapse. The aim is to avoid collapse. Earthquake actions in Australia AS Materials design Standards then provide detailing to enable the selected structural ductility to be achieved.