Alignment of South African National Building Regulation deemed-to-satisfy wall configurations to the loading code

Date
2023-03
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Stellenbosch : Stellenbosch University,
Abstract
ENGLISH ABSTRACT: The revision of the South African wind loading standard, SANS 10160-3 published in 2019, resulted in an increase of design wind load for South Africa of 11 % (Botha et al., 2019). Due to the cautious design restrictions of prior seismic standards, a new seismic loading standard, SANS 10160-4, was developed in 2009. However, since the deemed-to-satisfy walling solutions (SANS 10400-K) of the National Building Regulations (NBR) were created in 2000, they may not satisfy the most recent wind and seismic loading standards. The possible discrepancy between the National Building Regulations and South African loading standards could have an impact on the structural performance of South African masonry buildings. Many low-income housing owners have reported that the structure is inadequate and lacks quality. Furthermore, De Villiers (2019) showed that conventional masonry walls based on the NBR's deemed-to-satisfy solutions fail sustain the required design loads. With this said, there is still currently a housing shortage of 3.7 million (SA Stats, 2019) which is expanding at a rate of 178 000 units per year (Di Lollo et al., 2019). In addition, the government is struggling to meet the moving target and is shifting their policy to providing serviced land only which may increase self-builds. Therefore, it is required to conduct assessments on low-income housing that is subjected to wind and seismic loading according to SANS 10160-3 and SANS 10160-4. To analyse these discrepancies, various low-income housing buildings layouts were designed consisting of the most vulnerable wall configurations permitted by the National Building Regulations taking into account building energy usage, natural lightning, constructability, South African construction practice and skill level. Thereafter, the worst-case wind and seismic loadings according to South African loading standards are calculated and applied to the vulnerable wall configurations through computational modelling, using finite element analysis (DIANA FEA). To analyse the capacity of the wall configurations, the simplified micro-modelling approach was used together with two input parameter sets. The first parameter set represents masonry in South Africa's low-income housing general practice and is obtained through experimental results performed by Fourie (2017). The second parameter set represents the minimum requirements specified by the relevant South African standards. The results revealed that the majority of the deemed-to-satisfy wall configurations fail to meet the required ultimate limit state wind design load. Under ULS-S loading, the study findings indicate that the slenderness of the pier adjacent to the return wall governs the wall capacity. Therefore, SANS 10400-K does not provide sufficient requirements for deemed-to-satisfy panel walls and gable walls to sustain the ULS-W and SLS loading required by the updated wind loading standard of South Africa (SANS 10160-3, 2019) as well as the seismic loading standard (SANS 10160-4, 2017). It is recommended that the minimum required geometry requirements provided by SANS 10400-K (2011) as well as the minimum requirements for material parameters provided by the South African standards should both be increased to the ensure the subsequent structural capacity of the walls exceeds the design load required by SANS 10160-3 (2019) and SANS 10160-4 (2017).
AFRIKAANS OPSOMMING: Die hersiening van Suid-Afrika se windlas standaard, SANS 10160-3, wat in 2019 gepubliseer is, lei tot 'n toename in ontwerpwindlading van 11 % vir die hele land (Botha et al., 2019). As gevolg van die versigtige ontwerpbeperkings van vorige seismiese standaarde, is 'n nuwe seismiese standaard, SANS 10160-4, in 2009 ontwikkel. In teen deel, is die brevredigende muur oplossings (SANS 10400-K) van die Nasionale Bouregulasies (NBR) in die jaar 2000 ontwikkel en daarom neem dit nie die nuutste Suid Afrikaanse wind en seismiese las standaarde in ag neem nie. Die struktrurele prestasie van messelwerk mure in Suid-Afrika mag dalk beinvloed word deur die moontlike teenstrydighede tussen die Nasionale Bouregulasies en Suid-Afrika se las standaarde. Menigte lae-inkomstebehuising eienaars het geraporteer dat die struktuur is onvoldoende en van slegte gehalte. Verder het De Villiers (2019) se studie getoon dat konvensionele messelwerk mure gebaseer op die NBR se bevredigende oplossings nie die vereiste ontwerplaste kan dra nie. Met dit gesê, daar is tans 'n behuisingstekort van 3.7 miljoen (SA Statistieke, 2019) wat teen 'n tempo van 178 000 eenhede per jaar uitbrei (Di Lollo et al., 2019). Boonop sukkel die regering om die bewegende teiken te haal en verskuif hul beleid na die verskaffing van gedienste gronde wat self-bou kan verhoog. Gevolglik word dit vereis om die drae vermoë van lae-inkomstebehuising wat onderworpe is aan windlading en seismieselading volgens SANS 10160-3 en SANS 10160-4 te assesseer om te bepaal of dit voldoende is. Verskeie lae-inkomste behuisings uitlegte is ontwerp wat bestaan uit die mees kwesbare mure en wat voldoen aan die NBR wat energie gebruik, natuurlike lig, boubaarheid, Suid-Afrikaanse konstruksiepraktyk en vaardigheidsvlak insluit. Gevolglik word die ergste-geval wind en seismiese laste volgends die Suid-Afrikaanse las standaarde bereken en toegepas op die kwesbare muur konfigurasies met rekenaarmodellering met die gebruik van eindige element anailse (DIANA FEA). Die vereenvoudigde mikro-modellering benaderring was gebruik saam met twee invoerparameterstelle om die kapasiteit van die muur te analiseer. Die eerste stel parameters verteenwoordig die Suid- Afrikaanse lae-inkomstebehuising se algemene praktyk en word verkry deur eksperimentele resultate wat deur Fourie (2017) gedoen is. Die tweede stel parameters verteenwoordig die minimum vereistes gespesifiseer deur die Suid-Afrikaanse standaarde. Volgends die bevindinge het die meeste muurkofigurasies nie genoeg kapasitiet om die vereiste eindgrenstoestand (ULS) windontwerpslading te kan weerstaan nie. Terwyl die studiebevindinge onder vereiste eindgrenstoestand seismiese-ontwerpslading aandui dat die skraalheid van die pier langs die terugkeermuur die muurkapasiteit beheer. Dit wil sê, dat SANS 10400-K voorsien nie voldoende geometriese vereistes vir paneelmure en mure met gewels om die opgedateerde Suid-Afrikaanse eindgrenstoestand ontwerp windlading (SANS 10160-3, 2019) en seismiese lading (SANS 10160-4, 2017) te kan weerstaan nie. Dit word aanbeveel dat die minimum geometriese vereistes wat deur SANS 10400- K (2011) verskaf word, sowel as die minimum vereistes vir ateriaalparameters wat deur die Suid- Afrikaanse standaarde verskaf word, beide verhoog moet word om te verseker dat die kapasiteit van die mure die ontwerpslading wat deur SANS 10160-3 (2019) en SANS 10160-4 (2017) vereis word te oorskry.
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Thesis (MEng)--Stellenbosch University, 2023.
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