In-Plane Seismic Response of Unreinforced and Jacketed Masonry Walls

Senad Medić,Mustafa Hrasnica

doi:10.3390/buildings11100472

Abstract

Low-rise residential and public masonry structures constitute a large portion of the building patrimony, yet they were erected during the massive reconstruction of Southeast Europe after World War II before any design rules existed in the engineering praxis. Unreinforced unconfined masonry buildings (URM) were proven rather vulnerable during stronger earthquake motions in the recent past. To determine lateral strength, stiffness, and capacity of energy dissipation of the URM walls, in-plane tests were performed at the University of Sarajevo. Two full-scale plain walls (233 × 241 × 25 cm) built with solid clay brick and lime-cement mortar and two walls strengthened with RC jacketing on both sides were subjected to cyclic lateral loading under constant vertical precompression. Plain walls failed in shear with a typical cross-diagonal crack pattern. Jacketed walls exhibited rocking with characteristic S-shaped hysteretic curves and significantly larger ductility compared with plain walls. Wallets were tested for modulus of elasticity and compressive strength of masonry and the results showed considerable variations.

Highlights

The existing buildings in Bosnia and Herzegovina and the Western Balkan region are traditionally built as clay brick or stone masonry buildings
Most of the existing masonry buildings were built before the introduction of modern seismic codes, most commonly as unreinforced masonry without any confinement
It is a valuable contribution to the assessment of the in-plane behavior of masonry walls without vertical RC-confining elements, typical for low-rise masonry buildings in Bosnia and Herzegovina and the Balkan region

Summary

Introduction

The existing buildings in Bosnia and Herzegovina and the Western Balkan region are traditionally built as clay brick or stone masonry buildings. Several strong earthquakes hit the region of the Western Balkans in the last 50 years (Skopje 1963, Banja Luka 1969 and Montenegro Coast 1979), causing significant human losses and heavy damage to building structures, including partial and total collapse of some buildings [2,3]. This underlines the importance of seismic vulnerability assessment, which can lead to strengthening and retrofit measures, applied on load-bearing structures [4,5,6], and in soil and infrastructure [7,8]. The latest relatively moderate earthquakes that hit Croatia in 2020 resulted in heavy damage on the older masonry buildings in Zagreb and especially Petrinja, many of which have already been demolished [9,10]

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