Out-of-Plane Dynamic Stability of Unreinforced Masonry Walls in One-Way Bending: Shake Table Testing

2016 ◽  
Vol 32 (3) ◽  
pp. 1675-1697 ◽  
Author(s):  
Osmar Penner ◽  
Kenneth J. Elwood
Keyword(s):  
Ground Motion ◽  
Companion Paper ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Shake Table ◽  
Brick Wall ◽  
Test Results ◽  
Ground Motion Variability ◽  
Out Of Plane ◽  
Assessment Guidelines

Given sufficient anchorage to the diaphragms, an unreinforced masonry (URM) wall subjected to out-of-plane inertial forces will likely develop a horizontal crack at an intermediate height about which the wall will rock as semirigid bodies. The effect of wall slenderness on out-of-plane stability has been demonstrated in past studies, but treatment of the effects of diaphragm flexibility and ground motion variability has been limited. This paper presents an experimental study examining the out-of-plane stability under seismic loading of URM walls connected to flexible diaphragms. Five full-scale unreinforced solid clay brick wall specimens spanning one story were subjected to earthquake ground motions using a shake table. The top and bottom of the walls were independently connected to the shake table through coil springs, simulating the flexibility of diaphragms. Variables examined experimentally included diaphragm stiffness and wall height. Both the amount of rocking observed as well as the ground motion scale causing collapse varied significantly with changes in the diaphragm properties. The test results provided data used for validation of a rigid-body rocking model, enabling an extensive parametric study on wall stability and the development of new assessment guidelines in a companion paper.

Out-of-Plane Dynamic Stability of Unreinforced Masonry Walls in One-Way Bending: Parametric Study and Assessment Guidelines

2016 ◽  
Vol 32 (3) ◽  
pp. 1699-1723 ◽  
Author(s):  
Osmar Penner ◽  
Kenneth J. Elwood
Keyword(s):  
Parametric Study ◽  
Ground Level ◽  
Companion Paper ◽  
Unreinforced Masonry ◽  
Assessment Procedure ◽  
Ground Motion Variability ◽  
Rigid Body Model ◽  
Out Of Plane ◽  
Assessment Guidelines ◽  
Reference Curves

A numerical rigid body model for the out-of-plane response of unreinforced masonry (URM) walls connected to flexible diaphragms is validated against the shake table test results presented in a companion paper. It is demonstrated that the model is able to reproduce the observed rocking behavior with reasonable accuracy, particularly the intensity of shaking resulting in collapse of the walls. The validated model is used to undertake a parametric study investigating the effects of numerous parameters on out-of-plane wall stability. Ground motion variability is accounted for by using a large suite of motions. Based on the results of the modeling, an updated out-of-plane assessment procedure is proposed. The procedure, which could be incorporated into ASCE 41, provides reference curves of h/ t versus S a(1.0), along with correction factors for axial load, wall thickness, ground-level walls, and exposure.

Shake table tests on the out-of-plane response of unreinforced masonry wallsThis article is one of a selection of papers published in this Special Issue on Masonry.

2007 ◽  
Vol 34 (11) ◽  
pp. 1381-1392 ◽  
Author(s):  
C. S. Meisl ◽  
K. J. Elwood ◽  
C. E. Ventura
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Unreinforced Masonry ◽  
Rigid Bodies ◽  
Shake Table ◽  
Shake Table Tests ◽  
Out Of Plane ◽  
Wall Construction ◽  
Selection Of

Given sufficient anchorage to the diaphragms, out-of-plane walls in unreinforced masonry (URM) buildings have been shown to crack above midheight and then rock as two rigid bodies. This study investigates the sensitivity of the rocking response to the type of ground motion and the quality of the wall construction. Shake table tests were conducted on four full-scale multi-wythe walls, all with a height to thickness (h/t) ratio of 12 but of varying construction quality and subjected to three different ground motions. All walls experienced cracking at less than one half of the 2005 National Building Code of Canada (NBCC) level for Vancouver, but exhibited a stable rocking behaviour without collapse beyond a ground motion 1.5 times the 2005 NBCC level.

Full‐scale shake‐table tests on two unreinforced masonry cavity‐wall buildings: effect of an innovative timber retrofit

2021 ◽  
Author(s):  
Marco Miglietta ◽  
Nicolò Damiani ◽  
Gabriele Guerrini ◽  
Francesco Graziotti
Keyword(s):  
Seismic Vulnerability ◽  
Concrete Slab ◽  
Cost Effective ◽  
Unreinforced Masonry ◽  
Full Scale ◽  
Cavity Wall ◽  
Masonry Walls ◽  
Shake Table ◽  
Earthquake Excitation ◽  
Reinforced Concrete Slab

AbstractTwo full-scale building specimens were tested on the shake-table at the EUCENTRE Foundation laboratories in Pavia (Italy), to assess the effectiveness of an innovative timber retrofit solution, within a comprehensive research campaign on the seismic vulnerability of existing Dutch unreinforced masonry structures. The buildings represented the end-unit of a two-storey terraced house typical of the North-Eastern Netherlands, a region affected by induced seismicity over the last few decades. This building typology is particularly vulnerable to earthquake excitation due to lack of seismic details and irregular distribution of large openings in masonry walls. Both specimens were built with the same geometry. Their structural system consisted of cavity walls, with interior load-bearing calcium-silicate leaf and exterior clay veneer, and included a first-floor reinforced concrete slab, a second-floor timber framing, and a roof timber structure supported by masonry gables. A timber retrofit was designed and installed inside the second specimen, providing an innovative sustainable, light-weight, reversible, and cost-effective technique, which could be extensively applied to actual buildings. Timber frames were connected to the interior surface of the masonry walls and completed by oriented strands boards nailed to them. The second-floor timber diaphragm was stiffened and strengthened by a layer of oriented-strand boards, nailed to the existing joists and to additional blocking elements through the existing planks. These interventions resulted also in improved wall-to-diaphragm connections with the inner leaf at both floors, while steel ties were added between the cavity-wall leaves. The application of the retrofit system favored a global response of the building with increased lateral capacities of the masonry walls. This paper describes in detail the bare and retrofitted specimens, compares the experimental results obtained through similar incremental dynamic shake-table test protocols up to near-collapse conditions, and identifies damage states and damage limits associated with displacements and deformations.

Effect of in-plane damage on out-of-plane strength of unreinforced masonry walls

2013 ◽  
Vol 57 ◽  
pp. 1-11 ◽  
Author(s):  
Pawan Agnihotri ◽  
Vaibhav Singhal ◽  
Durgesh C. Rai
Keyword(s):  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Out Of Plane

scholarly journals Out-of-plane Strength of Existing Two-way Spanning Solid and Cavity Unreinforced Masonry Walls

Structures ◽  
2018 ◽  
Vol 13 ◽  
pp. 88-101 ◽  
Author(s):  
H. Derakhshan ◽  
W. Lucas ◽  
P. Visintin ◽  
M.C. Griffith
Keyword(s):  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Out Of Plane

scholarly journals A Study on Finite Element Modelling and Analysis with respect to Experimental Results of Strengthened Unreinforced Masonry Walls With and Without Kevlar-FRP

2021 ◽  
Vol 23 (2) ◽  
pp. 67-77
Author(s):  
Sugeng Wijanto ◽  
Takim Andriono ◽  
Jovita Tanudjaja
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Three Dimensional ◽  
Unreinforced Masonry ◽  
Shear Capacity ◽  
Masonry Walls ◽  
Test Results ◽  
Element Modelling ◽  
Laboratory Test Results ◽  
Set Up

Unreinforced masonry (URM) walls, found in most historical buildings in Indonesia, are relatively brittle with wide variety of material properties. The behaviour of URM walls is very complex, especially when subjected to seismic excitation. In this research, a finite element modelling was set up in order to analyse the seismic performance of URM wall experimental test units, with and without strengthening material. The analysis was conducted using SAP2000 computer program. Three dimensional solids and springs as link connectors were assigned to represent the masonry behaviour. This research aims to compare results obtained from the computer analysis and the previously conducted laboratory experiments. The effectiveness of Kevlar fibre material, which was installed on both wall surfaces and modelled as truss element was also investigated. It was found that the failure mechanisms shown by the SAP2000 model was similar to the laboratory test results. The use of Kevlar Fibre as strengthening material was found able to significantly increase the stiffness and shear capacity of the URM wall.

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