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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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. Materials design Standards then provide detailing to enable the selected structural ductility to be achieved. The aim is to avoid collapse.
AS _Earthquake Actions in Australia_pdf – Free Download PDF
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. Earthquake actions in Australia. 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. Also, as a result of the lower earthquake loads expected, the detailing required is minimal compared to ass for such countries as New Zealand.
The Standard assumes that structures are irregular as the vast majority of structures in Australia fail to achieve regularity. 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. Influence of site sub-soil conditions The site sub-soil conditions are grouped into 11770.4 categories 11770.4 Ae, Be, Ce, De or Ee ranging from hard rock to very soft materials.
The site hazard is determined from Section 3 of the Standard. It is calculated by a simple equation given in Section 6 of the Standard.
Once the horizontal design action is calculated from ae above information and the seismic weight of the structure, analysis can be carried out. Snow and ice actions Part 4: Earlier this year CSIR The analysis and materials design is where AS For the lowest values i.
AS 1170.4_Earthquake Actions in Australia_2007.pdf
Worked examples To illustrate the use of the Standard, following are some examples of the design required for various site conditions. Hazard at the site Once the appropriate annual probability of exceedance has been determined, AS Summary This paper provides a short guide and worked examples illustrating the use of AS 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.
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. 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. 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 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. This value is then multiplied by the probability factor kp to determine the site hazard value kpZ for the appropriate annual probability of exceedance.
Finally, the parts of the structure must be tied together and individually designed to perform. Determining the period of an existing structure, however, is a simple exercise involving measuring its vibrations. This is required for the highest hazard levels and tallest structures. Inter-storey drifts should be checked to ensure that parts such as stiff walls do not interfere with the seismic force resisting system.
Period of vibration of the structure The construction material, type of structure, and the period of the first mode of vibration all have an influence on the forces experienced by the structure. Therefore, the materials design Standards are much simpler a those required in high hazard areas.
Once the value of Mu is selected the structure must then be detailed to achieve that selected ductility. Process of designing for earthquake actions Earthquake actions are determined by considering the site hazard and the type and configuration of the structure.
Walls will usually require a check of 1107.4 resistance to face loading. A similar approach to reducing loads assuming a higher Mu value could be used where Z is high.
The use 1170.4 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: 11700.4 materials design Standards are then used to design the members for the required resistance including achieving the ductility assumed in determining the loads.
Permanent, imposed and other actions Part 2: The material in which the structure is laterally coupled to the ground provides the site class. Detailing rules to achieve these levels of ductility can be highly complex. A simple method for distributing the earthquake actions to the levels of the structure is provided.
AS Earthquake actions in Australia Worked examples_百度文库
The Standard also provides the means for 11700.4 earthquake loads on a structure by achieving set levels of ductility. For Australian conditions, where we have scant knowledge of the earthquake activity, we design for a lateral equivalent static load, 11704. the structure is particularly vulnerable to dynamic effects. 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 load is then defined for any annual probability of exceedance so that the design event is independent of the technical definition of the loads.
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 standard also sets out minimum detailing requirements that aim to provide buildings with a reasonable level of ductility. The examples assume that at least a static analysis has been selected, and therefore, sets out the data required to calculate the base shear.
The ductility is achieved by applying the detailing provided in the materials design Standards currently in use. Selecting the analysis method Once the annual probability of exceedance, the hazard value for the site, the sub-soil conditions and the building height 11170.4 known, the required design effort can be determined using Table 2.
Earthquake actions in Australia AS The soil type is determined by a geotechnical investigation for taller longer period structures. 170.4 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 Australian Standard provides for simplified analysis methods based on the low level of hazard. 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.