The seismic analysis of a typical South African unreinforced masonry structure

Van Der Kolf, Thomas (2014-04)

Thesis (MEng)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: South Africa has some regions which are susceptible to moderate seismic activity. A peak ground acceleration of between 0.1g and 0.15g can be expected in the southern parts of the Western Cape. Unreinforced Masonry (URM) is commonly used as a construction material for 2 to 4 storey buildings in underprivileged areas in and around Cape Town. URM is typically regarded as the material most vulnerable to damage when subjected to earthquake excitation. In this study, a three-storey URM building was analysed by applying seven earthquake time-histories, that can be expected to occur in South Africa, to a finite element model. Experimental data was used to calibrate the in- and out-of-plane stiffness of the URM. A linear modal dynamic analysis and non-linear implicit dynamic analysis were performed. The results indicated that tensile cracking of the in-plane piers was the dominant failure mode. The building relied on the postcracking capacity to resist the 0.15g magnitude earthquake. It is concluded that URM buildings of this type are at risk of failure especially if sufficient ductility is not provided. The results also showed that connection failure must be investigated further. Construction and material quality will have a large effect on the ability of typical URM buildings to withstand moderate magnitude earthquakes in South Africa.

AFRIKAANSE OPSOMMING: Sekere gebiede in Suid-Afrika het ’n risiko van matige seismiese aktiwiteit. Aardbewings met maksimum grondversnellings van tussen 0.1g en 0.15g kan in die suidelike gedeeltes van die Wes- Kaap voorkom. Twee- tot vier-verdieping onbewapende messelwerkgeboue kom algemeen voor in die lae sosio-ekonomiese gebiede van Kaapstad. Oor die algemeen word onbewapende messelwerkgeboue as die gebou-tipe beskou wat die maklikste skade opdoen tydens aardbewings. In hierdie studie is sewe aardbewings, wat tipies in Kaapstad verwag kan word, identifiseer en gebruik om ’n tipiese drie-verdieping onbewapende messelwerkgebou te analiseer. Eksperimentele data is gebruik om die materiaaleienskappe in die in-vlak asook uit-vlak rigtings te kalibreer. Beide ’n liniêre modale en nie-liniˆere implisiete dinamiese analises is uitgevoer. Die resultate dui daarop dat die dominante falingsmode die kraak van in-vlak messelwerk-tussenkolomme is. Die gebou moes sy plastiese kapasiteit benut om die 0.15g aardbewing te kan weerstaan. Die gevolgtrekking is dat dié tipe onbewapende messelwerkgeboue ’n risiko inhou om mee te gee, veral as genoegsame vervormbaarheid nie verskaf word nie. Die resultate toon ook dat konneksie-faling verder ondersoek moet word. Kwaliteit van vakmanskap en van materiaal het ’n groot invoed op die vermoë van onbewapende messelwerkgeboue om aardbewings van matige intensiteit in Suid-Afrika te weerstaan.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/86588
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