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.

scholarly journals Finite Element Analysis for The Response of URM Walls Supporting RC Slab

2018 ◽  
Vol 7 (4.20) ◽  
pp. 259
Author(s):  
Ammar Rafid Ahmed ◽  
Alaa H. Al-Zuhairi
Keyword(s):  
Finite Element ◽  
Concrete Slab ◽  
Unreinforced Masonry ◽  
Masonry Walls ◽  
Reinforced Concrete Slab ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Rc Slab ◽  
Implicit Solver ◽  
Masonry Units

The aim for this research is to investigate the effect of inclusion of crack incidence into the 2D numerical model of the masonry units and bonding mortar on the behavior of unreinforced masonry walls supporting a loaded reinforced concrete slab. The finite element method was implemented for the modeling and analysis of unreinforced masonry walls. In this paper, ABAQUS, FE software with implicit solver was used to model and analyze unreinforced masonry walls which are subjected to a vertical load. Detailed Micro Modeling technique was used to model the masonry units, mortar and unit-mortar interface separately. It was found that considering potential pure tensional cracks located vertically in the middle of the mortar and units shows an increase in masonry strength of about 10% than the strength calculated using the procedure recommended by the Masonry Society Joint Committee in the building code.  

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.

Full scale experimental tests and numerical model validation of reinforced concrete slab subjected to direct contact explosion

2019 ◽  
Vol 132 ◽  
pp. 103309 ◽  
Author(s):  
Andrew Ruggiero ◽  
Nicola Bonora ◽  
Giuseppe Curiale ◽  
Stefano De Muro ◽  
Gianluca Iannitti ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Numerical Model ◽  
Model Validation ◽  
Direct Contact ◽  
Concrete Slab ◽  
Experimental Tests ◽  
Full Scale ◽  
Reinforced Concrete Slab ◽  
Contact Explosion

Simulating the shake table response of unreinforced masonry cavity wall structures tested to collapse or near-collapse conditions

2020 ◽  
Vol 36 (2) ◽  
pp. 554-578 ◽  
Author(s):  
Daniele Malomo ◽  
Rui Pinho ◽  
Andrea Penna
Keyword(s):  
Failure Modes ◽  
Unreinforced Masonry ◽  
Cavity Wall ◽  
Shake Table ◽  
Structural Members ◽  
Global Response ◽  
House Construction ◽  
Wall Structures ◽  
Out Of Plane ◽  
Applied Element Method

The seismic performance of existing unreinforced masonry (URM) buildings is considerably affected by typology and level of effectiveness of both construction details and structural components, especially if not originally designed for resisting earthquakes. Within this framework, the use of advanced numerical approaches that are capable of duly accounting for such aspects might improve significantly the assessment of the global response of URM structures. In this article, the applied element method is thus employed for simulating the shake table response of a number of full-scale building specimens representative of cavity wall terraced house construction, used in a number of countries exposed to tectonic or induced seismicity, accounting explicitly for the influence of the presence of both rigid and flexible diaphragms, degree of connections among structural members, and interaction between in- and out-of-plane mechanisms. Although the models slightly underestimated the energy dissipation in some specific cycles prior to collapse, the predicted crack patterns, failure modes, and hysteretic behaviors have shown a good agreement with their experimental counterparts.

Dimension and Frequency Profiles of Concrete Highway Bridges in New Madrid Region of Southeastern Missouri

1997 ◽  
Vol 1594 (1) ◽  
pp. 84-93 ◽  
Author(s):  
Ralph Alan Dusseau
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Highway Bridges ◽  
Ambient Vibration ◽  
Earthquake Hazards ◽  
Empirical Formulas ◽  
Reinforced Concrete Slab ◽  
Box Girder ◽  
Bridge Spans ◽  
New Madrid

The results of a study funded by the U.S. Geological Survey as part of the National Earthquake Hazards Reduction Program are presented. The first objective of this study was the development of a database for all 211 highway bridges along I-55 in the New Madrid region of southeastern Missouri. Profiles for five key dimension parameters (which are stored in the database) were developed, and the results for concrete highway bridges are presented. The second objective was to perform field ambient vibration analyses on 25 typical highway bridge spans along the I-55 corridor to determine the fundamental vertical and lateral frequencies of the bridge spans measured. These 25 spans included six reinforced concrete slab spans and two reinforced concrete box-girder spans. The third objective was to use these bridge frequency results in conjunction with the dimension parameters stored in the database to develop empirical formulas for estimating bridge fundamental natural frequencies. These formulas were applied to all 211 Interstate highway bridges in southeastern Missouri. Profiles for both fundamental vertical and lateral frequencies were then developed, and the results for concrete highway bridges are presented.

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