Ponašanje neduktilnih armirano-betonskih okvira sa zidanim ispunom na djelovanje potresa
Unreinforced masonry infills are often used as exterior and interior partitions in reinforced concrete frame building. Obtained system is economical and architecturally appealing and functional and as such is common in regions of medium and high seismicity world wide. Particular case that needs special attention are nonductile reinforced concrete frames with masonry infill. Their inherent weaknesses significantly contribute to seismic vulnerability and can lead to collapse of buildings during earthquake. Although first experimental researches dates from the 50-ies of last century, development of major research centers sparked momentum in experimental and numerical research of the seismic behavior if infilled frames. Nevertheless, literature survey reveals relatively small number of researchers that covers inherent weaknesses and characteristics of the behavior of nonductile infilled frames, which vas the main motivation of this study. Without distinguishing designed earthquake resistance, seismic behavior of infilled frames still remains a controversial question in research and structural engineering community due to the variety and complexity of observed failure mechanisms which are highly governed by the frame – infill interaction. Additional uncertainties such as lack of reliable model for assessment of stiffness and strength, where strength and stiffness of sistem can not be determined based od superposition of elements contribution, have lead to absence of rational assessment method in practise and modern seismic codes. Although modern seismic codes recognize influences of masonry infill, it is still treated as non-structural element while the frame – infill interaction is either completely ignored or treated trough application of diagonal strutt model. Only guidelines for a prevention of negative influence, such as premature shear failure of frame columns are given. To distinguish between designed earthquake resistance, nonductile frames with masonry infill are here in defined as framed masonry. This dissertation addresses intricate issue of seismic behavior of framed masonry sistem with experimental and analytical studies. The testing programe involved construction and tests of a 3 nonductile reinforced concrete bare frames and 11 one-span, one-storey framed masonry specimens. Additionally, properties of all used materials were also tested. All specimens were one half scaled and tested under nearly constant vertical and cyclic horizontal load. Geometrical and material parameters of test specimens were chosen with the aim to replicate inherent weaknesses of framed masonry systems and categorization of their influence on seismic behavior. Based on the element of the sistem, parameters are separated into two groups. First gropu of parameters addresses frame properties in terms of geometrical and reinforcement characteristics where total of 4 different frame configurations were chosen. Second group of parameters addresses infill properties where the variation is achieved with the use of two types of masonry elements and mortar. Obtained experimental data was used for the validation of existing analytical assessment methods and proposal of a new method. The proposed model is defined in terms of selected limit states and gives possibility of the assessment of strengths and drifts in respect to the observed seismic behavior of test specimens. The proposed analytical approach estimates seismic response reasonably well and thus can be used for the seismic assessment of existing framed masonry buildings. Additionally, estimation of seismic drifts for three levels of seismic hazard is conducted. Applied method was developed and validated at the University of Illinois at Urbana – Champaign, USA. Classification of damage degres was carried out according to the recommendations given in literature were bare frame and framed masonry specimens are considered separately. Obtained results indicated that masonry infill significantly reduces seismic drift regardless of seismic hazard level. Seismic drift reduction greatly contributes to the global stability of the framed masonry buildings. Furthermore, results indicates that masonry infills can be used as a mean of a seismic strengthening.
|Creator||Gazić, Goran (Search Europeana for this person)|
|Collection||Josip Juraj Strossmayer University of Osijek. Faculty of Civil Engineering.|
|Subject Terms||TECHNICAL SCIENCES. Civil Engineering. Supporting Structures., Civil and structural engineering. Civil engineering of land transport. Railway engineering. Highway engineering, framed masonry, experimental research, proposed analytical method for the seismic assessment, damage degres, mean of a seismic strengthening|
|Provider||National and University Library in Zagreb|