Wall Index Requirements for Seismic Design and Assessment of Masonry Buildings

Abstract

Wall Index (WI), also known as "wall density", is a ratio of the total cross-sectional area for all structural walls aligned in one direction of the building's floor plan and the gross floor plan area. Reconnaissance studies after past earthquakes in countries like Chile, Mexico, and China, confirmed that WI is one of the key parameters related to seismic performance of loadbearing masonry structures which influences the extent of earthquake damage. The WI requirements have been included in several international codes and guidelines. According to Eurocode 8 (EN 1998(EN :1-2005, WI can be used as a design parameter for seismic design of simple masonry buildings with regular configuration and limited height up to 5 storeys, as an alternative to a more elaborate and complex seismic analyses approaches. The required WI for a building depends on the seismic hazard for the building site, number of storeys, type of masonry (unreinforced/ reinforced/confined) and the mechanical properties of masonry (compressive/shear strength). WI can be also used for seismic assessment of existing masonry buildings in pre-and postearthquake situations, as documented by studies from Chile and Mexico. The paper will provide a comparison of the masonry design requirements from selected codes, including the 1964 and 1981 Yugoslav technical regulations for design and construction of buildings in seismic regions and Eurocode 8. A case study of a masonry residential building which was damaged in the 2010 Kraljevo earthquake (M 5.5) and evaluated using different codes is also presented in the paper.

Analysis and Design of Confined Masonry Structures: Review and Future Research Directions

“…Despite being designed to withstand vertical loads, masonry structures may still experience critical failure modes when subjected to gravity and lateral seismic loading, as the low tensile strength of masonry can become a limiting factor. As reported in past literature, CM buildings have performed excellently during earthquakes [8,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. Observations made during past earthquakes have revealed damage to CM buildings that had some design and construction flaws.…”

“…The ability of CM structures to resist structural loading is achieved through the combined action of the masonry walls and the adjacent RC confining elements, including tie-columns and tie-beams as well as a combination of plinth bands, sill bands, lintel bands, and roof slabs [7,8,[12][13][14][15][16]. In CM, failure due to only vertical loading is not considered a critical issue since masonry walls are always designed such that they are subjected to relatively less axial compressive stress.…”

“…These flaws included the use of poor-quality materials, insufficient tie-columns at wall intersections and around openings, a lack of detailing in the RC tie-columns, insufficient anchorage of reinforcement in the tie-elements, poor diaphragm connections, and torsional issues due to irregularities, among others. Past earthquake damage reports and research studies have identified several potential failure modes of CM buildings, which include in-plane failure, overturning or out-of-plane (OOP) failure, diaphragm failure, connection failure, and non-structural failure [8,18,32].…”

“…To achieve safe and affordable housing while preserving the authenticity of ma construction, various methods of reinforcing masonry walls have emerged over the Confined masonry (CM) is one such housing typology that has been proven to be sa affordable. Initially developed for rebuilding the buildings damaged during the 1908 sina (Italy) earthquake that had a 7.2 magnitude, the CM technique has since spre high-seismic-risk countries such as Mexico, Colombia, Chile, and various other cou [7][8][9]. CM is utilized in non-engineered and engineered residential construction, ra from single-to six-storey buildings.…”

Structural Performance of Energy Efficient Geopolymer Concrete Confined Masonry: An Approach towards Decarbonization

“…It was introduced in Italy and Chile in the wake of disastrous earthquakes, namely the 1908 Messina and 1929 Talca quakes, respectively [10]. Confined masonry, which is widely used for housing in Mexico [11] and most Latin-American countries [12][13][14][15], is also a common construction technique in several European countries such as Italy, Portugal, and Slovenia [16][17][18], as well as Asian countries including Iran [19,20], Indonesia [21], Pakistan [22], and China [16,23]. In areas with moderate to high seismic activity, confined masonry has been used as a common building technique for low-to mid-rise structures [24,25].…”