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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For the lowest values i. 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 design using the design event approach. The Table below shows how for many structures, there are points at 1710.4 no further work is required. The Standard also provides the means for reducing earthquake loads on a structure by achieving set levels of ductility.
1107.4 the base shear For the vast majority of structures low height, normal importance on firm or shallow soils the next step is to estimate if the load is likely to be less than the wind load.
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 site hazard is determined from Section 3 of the Standard. 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. 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.
The ductility is achieved by applying the detailing provided in the materials design Standards currently in use. It is calculated by a simple equation given in Section 6 of the Standard. The basic aim is to state the design event in terms of the annual probability of the action being exceeded. The Australian Standard provides for simplified analysis methods based on the low level of hazard.
Process of designing for earthquake actions Earthquake actions are determined by considering the site hazard and the type and configuration of the structure.
AS _Earthquake Actions in Australia_pdf – Free Download PDF
Therefore, it is not expected that a structure subject to the design earthquake would be undamaged, but rather that the damage ss not progressed to collapse. Summary This paper provides a short guide and worked examples illustrating the use of AS General principles provides the link between the limit states actions imposed on the structure and the design of materials for resistance.
The load is then defined for any annual probability of exceedance so that the design event is independent of the technical definition of the loads. Generally, for short structures that are not of high importance, simply knowing whether the structure sits on rock or in soils of some depth eg.
Determining the period of 117.4 existing structure, however, is a simple exercise involving measuring its vibrations. The base shear may be understood to be the percentage of the weight of the building to be applied laterally eg. Earlier this year CSIR Hazard at the site Once the appropriate annual probability of exceedance has been determined, AS Earthquake actions in Australia.
This is zs for the highest hazard levels and tallest structures.
Finally, the parts of the structure must be tied together and individually designed to perform. Earthquake actions in Australia AS This was a group of loading experts from across the APEC region that met to create a means of establishing inter-changeability between the loading codes of different nations.
The Standard assumes that structures are irregular as the vast majority of structures in Australia fail to achieve regularity. Many structures do not require this level of design effort as there are conditions for which no further work is required by 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.
In order to achieve the ductility assumed in design of the structure, it is essential that stiff elements should not impose themselves on the behavior of 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. 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.
For dynamic analysis, the effects of a number of periods of vibration may 1710.4 summed to determine the action effects in the members and, therefore, a number of spectral shape factors may be used in the analysis. 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.
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 standard also sets out minimum detailing requirements that aim to provide buildings with a reasonable level of ductility.
AS 1170.4_Earthquake Actions in Australia_2007.pdf
This value is then multiplied by the probability factor kp to determine the site hazard value kpZ for the appropriate annual probability of exceedance. Snow and ice actions Part 4: Materials design Standards then provide detailing to enable the selected structural ductility to be achieved. The value of Z can be read from a Table or, for locations away from major centres of population, determined from the maps. The materials design Standards are then used to design the members for the required resistance including achieving the ductility assumed in determining the loads.
Influence of site 110.4 conditions The site sub-soil conditions are grouped into 5 categories Class Ae, Be, Ce, De or Ee ranging from hard rock to very soft materials. The loads 170.4 the structure are then 117.04 based on this value. Wind actions Part 3: 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.