Assessment of compressive strength of historic mixed masonry

Abstract

The majority of load-bearing masonry structures of historic buildings are built of mixed or stone masonry composed of regular or irregular (so-called quarry) masonry units – bricks, sedimentary and metamorphic rock – possessing often very different physical and mechanical characteristics. The identification of residual mechanical properties of stone or mixed masonry of irregular walling units requires the application of a suitable diagnostic method, the assessment of the phase of degradation processes and the choice of an appropriate probabilistic model for the strength of mixed masonry. The presented experimental research involves the analysis of the heterogeneity (homogeneity) of mixed masonry of a church from the 17^th century. The probabilistic model for masonry strength is developed on the basis of destructive and non-destructive testing of masonry units and mortar. It appears that the probabilistic approach leads to a design value by 75% higher than the deterministic approach.

Keywords:

• mixed masonry
• stone masonry
• destructive test
• non-destructive test
• probabilistic model
• masonry strength

Additional information

Notes on contributors

Jiří Witzany

Jiří WITZANY. Professor, DrSc, Dr h.c., Eng., Rector Emeritus, Dean FCE CTU 1990–1996, Rector CTU 2000–2006, Department of Building Structures (Head of the Department 1990–2008), Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic. Professional activities during last 10 years: Chief researcher of 2 research plan and 10 grant, author and co-author of 10 monographs, 10 utility designs, 5 patents, 58 scientific and professional articles and over 80 papers on national and international conferences, 25 research reports. He devoted himself to structural problems of designing building structures, has carried out extensive theoretic and experimental research of prefabricated and masonry structures, reconstruction and rehabilitation designs of concrete and masonry buildings, strengthened of masonry structures by CFRP and GFRP, degradation processes, durability and reliability of buildings. He has designed the reconstruction concept of the midlle age Charles Bridge in Prague.

Tomáš Čejka

Tomáš ČEJKA. Assoc. Professor, PhD, Eng. at the Department of Bulding Constructions, Faculty of Civil Engineering, Czech Technical University in Prague, Czech Republic. Professional activities during last 10 years: Co-researcher of 2 research plan and 10 grant, co-author of 8 monographs, 10 utility designs, 38 scientific and technical articles and over 48 papers on national and international conferences, 18 research reports. His research interests include structural analysis, mainly of masonry and precast concrete structures, reconstructions and renovations of buildings, etc.

Miroslav Sýkora

Miroslav SÝKORA. Eng., PhD, Czech Technical University in Prague, Klokner Institute. His research interests include basis of structural design, structural reliability, probabilistic optimisation, load modelling, risk assessment of technical systems and applications of probabilistic methods in structural design. He is an author or co-author of several handbooks for practising engineers and a number of scientific publications (more than 100, most of them in English). He is a member of the Joint Committee on Structural Safety, fib (Activity Group 7 Assessment and Interventions upon Existing Structures) and the Czech national contact for the Horizontal Group – Bridges of CEN.

Milan Holický

Milan HOLICKÝ. Prof., Eng., PhD, DrSc, Czech Technical University in Prague, Klokner Institute. He is involved in the research of structural reliability and risk assessment. He is the author or co-author of more than 300 scientific and technical publications, including textbooks and five monographs. Since 1991, he has represented the Czech Republic on the European Committee for Standardisation (CEN) as a member of the Technical committee TC 250 “Structural Eurocodes”. In 2010 he became Extraordinary Professor at the University of Stellenbosch, South Africa; in 2011 he was awarded the Honorary Doctor of Science and Engineering degree from Moscow State University of Civil Engineering.