Numerical investigations on the seismic behaviour of confined masonry walls (original) (raw)
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Confined masonry (CM) is a construction system which consists of masonry wall panels enclosed by vertical and horizontal reinforced concrete confining elements. The presence of these confining elements distinguishes CM from unreinforced masonry system and makes this technology suitable for construction of structures in regions subjected to intense seismic or wind actions. CM construction has been used in many countries and regions, and has performed well in past earthquakes. The purpose of the paper is to review past research studies related to the seismic in-plane and out-of-plane behaviour of CM structures. The authors have identified the key design and construction parameters which were considered in past research studies and have performed statistical analyses to establish their influence on the seismic performance of CM buildings. For the purpose of this study the authors have compiled databases of previous experimental studies on CM wall specimens which were used for statistic...
Seismic behaviour of confined masonry walls
Earthquake Engineering & Structural Dynamics, 1997
The results of tests of plain and confined masonry walls with h/l ratio equal to 1•5, made at 1 : 5 scale, have been used to develop a rational method for modelling the seismic behaviour of confined masonry walls. A trilinear model of lateral resistance-displacement envelope curve has been proposed, where the resistance is calculated as a combination of the shear resistance of the plain masonry wall panel and dowel effect of the tie-columns' reinforcement. Lateral stiffness, however, is modelled as a function of the initial effective stiffness and damage, occurring to the panel at characteristic limit states. Good correlation between the predicted and experimental envelopes has been obtained in the particular case studied. The method has been also verified for the case of prototype confined masonry walls with h/l ratio equal to 1•0. Good correlation between the predicted and experimental values of lateral resistance indicates the general validity of the proposed method.
Influential aspects on seismic performance of confined masonry construction
Natural Science, 2013
Recent earthquakes around the world have resulted in loss of human lives and high economic losses due to poor performance of unreinforced masonry constructions as well as poorly-built reinforced concrete framed buildings. This has necessitated alternative building technologies with improved seismic performance. Confined masonry (CM) construction, has shown excellent behavior during past earthquakes across the world and requires similar skill at a marginally higher cost than that of unreinforced masonry. This paper summarizes the main features of generic construction and gains insight into the behavior of CM elements under earthquake excitations, representing a viable alternative for safe and economical construction in seismic areas. The paper discusses various influential aspects like sequence of construction, properties and type of masonry material, structural configuration, reinforcement detailing in tie column/beam and masonry, panel aspect ratio, interface between concrete and masonry, axial stress, multiple confining column, opening in wall panels and damage pattern etc. along with solution to overcome the limitations.
Experimental and Numerical Assessment of Confined and Unreinforced Brick Masonry Structures
2019
Brick masonry is widely used for building construction throughout the world. However, unreinforced brick masonry buildings performed poorly in the 2005 Kashmir earthquake, in Pakistan, resulting in a decline in the use of masonry construction. To investigate and quantify the performance of masonry against the seismic forces by confining it through typical stiffer, line elements (column and beams), a full-scaled room model of an area 3048 × 3658mm (10 × 12 ft) and height of 3353mm (11 ft) was constructed using confined brick masonry and tested under quasi-static cyclic loading. Damage details were observed after each loading cycle. The structure's response was interpreted through a hysteresis curve, after which the envelop curves were drawn and the envelop curve was then converted into bilinear curve for determining different limit states and performance levels. A comparison 2.7.2 Predominant design failures in confined masonry during Earthquakes .......
Structural Response of Unreinforced Masonry Walls
Journal of Civil Engineering and Architecture, 2016
Historical buildings located in seismic regions have URM (unreinforced masonry) walls of considerable width as their main structure. In order to study the structural response of such type of masonry, it is necessary to know its mechanical and elastic characteristics. For such purpose, it is generally necessary to perform destructive and non-destructive tests. Other procedures, such as the study of masonry through numerical models, would make it possible to predict, with close approximation, the response of masonry to different actions. The purpose of this paper is to evaluate the behavior of URM walls subjected to axial and horizontal load by using a finite element model with the Abaqus code. Constitutive laws of materials, bricks and mortar are defined, using two constitutive models of plasticity and damage included in the materials library. The constitutive models used employ information of experimental tests performed on bricks and mortar. The results of an analysis for an URM wall subjected to axial and horizontal load are presented. Responses of walls were obtained in terms of load versus displacement for different constitutive models and for different qualities of bricks and mortar. The two constitutive models used show similar results, particularly in the response waveforms. However, the ultimate capacity values show mean variations of around 30%. The two constitutive models display high dependence upon the mechanical characteristics of bricks and mortar.
Theoretical and Experimental Engineering Analysis for Seismically Damaged Masonry Buildings
2001
Romania is one of the countries undergoing a persistent, periodical severe seismic regime, generated by sources of tectonic origin. The strongest earthquakes occurring in our country are of an intermediary, subcrustal (70<H<170 km) type, having active focuses and standing for seismic phenomena unique throughout the world due to their strength, the geometric, kinematic and dynamic characteristics of their focuses and to their generating mechanism. This type of earthquakes is of utmost importance within the total number of earthquakes occurring on the territory of our country, having also the strongest intensities. Masonry construction is commonly employed in Romania and a large portion of the supporting elements in building structures consists of this material. Most of these structures are not aseismic designed, the elements are nor fit to transfer the earthquake forces and thus they must therefore be post-strengthened. For the evaluation of the resisting capacity to gravitational and seismic actions experimental and numerical methods of investigation were applied. The paper presents the steps followed in postseismic investigation and the strengthening solutions adopted for some masonry buildings, both monumental and usual constructions.
OUT-OF-PLANE SEISMIC RESISTANCE OF MASONRY WALLS
Journal of Earthquake Engineering, 2001
Seismic vulnerability of unreinforced masonry buildings is studied by means of simplified out-of-plane collapse mechanisms that take into account connections with transversa1 walls. According to experimental evidence, the analysis assumes that faiIure is reached with a rigid body motion of a part of the fqade that falls down. Two classes of mechanism are examined: the overturning of the fqade due either to a vertical crack a t the connection or a diagonal crack on the transversal wall, both defined resorting to a simple model of masonry fabric, viewed as a regular assembly of rigid blocks and elastic plastic joints with friction but no cohesion. The use of simplified mechanisms give rise to an explicit evaluation of the seismic resistance to changes in the geometry and in the masonry fabrics, that could be used by practising engineers. This formulation is developed for both static horizontal actions and ground velocity peak, in the belief that the latter probably gives a better approximation of seismic action, while also providing, by comparison with the results of static forces, an estimate of the behaviour factor lor unreinforced masonry. Eventually, the analytical forec-ts are compared with numerical results obtained by means of the distinct element method.
Earthquake Engineering & Structural Dynamics, 2006
To improve the seismic performance of masonry structures, confined masonry that improves the seismic resistance of masonry structures by the confining effect of surrounding bond beams and tie columns is constructed. This study investigated the earthquake resisting behaviour of confined masonry structures that are being studied and constructed in China. The structural system consists of unreinforced block masonry walls with surrounding reinforced concrete bond beams and tie columns. The characteristics of the structure include: (1) damage to blocks is reduced and brittle failure is avoided by the comparatively lower strength of the joint mortar than that of the blocks, (2) the masonry walls and surrounding reinforced concrete bond beams and tie columns are securely jointed by the shear keys of the tie columns. In this study, wall specimens made of concrete blocks were tested under a cyclic lateral load and simulated by a rigid body spring model that models non-linear behaviour by rigid bodies and boundary springs. The results of studies outline the resisting mechanism, indicating that a rigid body spring model is considered appropriate for analysing this type of structure.
Dynamic Analysis of Confined Masonry Structures for Residential Buildings under Seismic Conditions
International Journal for Research in Applied Science & Engineering Technology (IJRASET), 2022
In India, unreinforced brick masonry and reinforced cement concrete are the go-to technologies when it comes to construction of modern residential buildings, with the design applications ranging from one-story nuclear family houses to multi-story apartment buildings housing several families. However, each major natural disaster in India has exposed several 'chinks in the armour' linked to both of these widely employed construction techniques. Enter confined masonry. Confined masonry offers a substitute to both, unreinforced brick masonry and reinforced concrete framed residential buildings for applications in disaster prone areas of the world while keeping the cost under check and optimizing the structural performance. Confined masonry has evolved over the last century through an informal process based on its satisfactory performance in past, mostly in countries with high seismic activity like Indonesia, Mexico and Turkey. It is used for both non-engineered and engineered construction as its field applications range from one-story single-family dwellings to six-story apartment buildings. Some countries have even adopted design provisions and construction guidelines for confined masonry in their building codes. The success and implementation of building technologies is totally dependent on the local conditions like the availability and cost of building materials, the skill level of construction labour and the availability of construction tools and equipment. The fact that confined masonry construction looks similar to reinforced frame construction with masonry infill walls and that it uses the same components, i.e., masonry infills, tie-beams and tie-columns, helps in an easy transition to adopt confined masonry. Although confined masonry construction practice doesn't require any advanced construction equipment or an extra skillset, it is necessary to lay emphasis on the quality of the construction for its satisfactory performance. Hence, to optimize the quality of confined masonry structures, this thesis employs the use of a modern easy-to-learn-and-use structural software known as ETABS.
A Comparative Study on the Seismic Performances of Unreinforced and Confined Masonry Buildings
2018
Confined masonry (CM) buildings constitute a superior sub-class of masonry construction when compared to unreinforced masonry (URM) buildings in terms of seismic performance. Accordingly, this type of construction is very popular in South American Countries and in some regions of Asia. However until now, this has not been the case in Turkish construction practice, where nearly 30% of the total building stock is composed of URM buildings but a negligible percent of CM buildings. The main reason is to ignore CM construction in Turkey and not to promote it in the previous and the current seismic codes. But now, on the verge of releasing a new version of Turkish seismic code, there exist some attempts to adapt regulations concerning CM construction into the new code. This study tries to validate such attempts by comparing the seismic performances of URM and CM buildings starting from the component level up to the structural level. In order to assess the performances of these building ty...