Experimental Research Studies on Seismic Behaviour of Confined Masonry Structures: Current Status and Future Needs (original) (raw)

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.

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...

Seismic performance assessment of confined masonry construction at component and structure levels

Bulletin of Earthquake Engineering, 2018

There are different techniques for masonry construction. Among these, confined masonry (CM) buildings may be regarded as an upgrade for unreinforced masonry (URM) buildings, which is the most common type. In Turkey, URM construction has been popular, especially up to the end of 1980s. These rather old URM buildings constitute a significant percent of the existing building stock. On the other hand, CM construction seems to be rare when compared to its URM counterpart in Turkey. This fact was also reflected in older versions of the Turkish seismic design codes as clauses regarding CM construction did not exist in these codes. In 2018, a new version of the Turkish seismic design code has been released, taking into account CM construction for the first time explicitly. In accordance with this fact, this study presents a comparison between the seismic performances of URM and CM building types at component and structure levels. The first phase of the study focuses on the capacity curves of URM and CM walls that have been idealized by using a piece-wise linear model with different performance limits. Empirical formulations from previous research are examined to determine the capacity curve parameters with the premise that they have the best estimate for the selected experimental dataset concerning URM and CM wall specimens. The second phase deals with the seismic performance in structure level for URM and CM buildings that are composed of masonry walls with idealized capacity curves as obtained in the first phase of the study. Capacity Spectrum Method is used for the analyses. The results reveal the superior behavior of CM construction over URM construction during seismic action.

Effects of Construction Methods on Seismic Behavior of Confined Masonry Walls-An Experimental Study

2012

The aim of this paper is to study experimentally conventional constructing methods of confined masonry buildings in Iran and to investigate differences in the seismic behavior of them. In present study the effect of mortar head joints, soaking bricks and extending lintel to the vertical ties in the behavior of confined masonry walls are considered. A series of experimental study are conducted on confined masonry walls in IIEES (International Institute of Earthquake Engineering and Seismology) laboratory. It includes 7 wall specimens which are tested under lateral cyclic loading. Two of them are without mortar head joints, three others are with central opening with and without lintel band and the others are solid walls with filled head joints. Bricks are fired clay bricks and ties are made up of cast-in-place reinforced concrete. Results of these tests are presented and effect of head joints, soaking bricks and extending lintel on overall behavior of them are discussed.

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

Buildings

This article discusses the significance of confined masonry (CM) structures in terms of their remarkable seismic performance in past earthquake events. However, the variability of CM structures with differing materials, detailing, and construction practices across different regions poses challenges in developing standardized design guidelines. To address the challenges, the state-of-the-art developments in CM are comprehensively reviewed in the present article. This review encompasses experimental campaigns studying CM walls and buildings to evaluate the effect of important parameters on their performance, a discussion of various numerical and analytical models with their respective benefits and limitations, and an examination of design procedures for CM in nine country codes and their local guidelines. This review identifies gaps in the current knowledge, including the need for more studies on the performance of CM structures under earthquake loads and the use of new materials and ...

An Overview of Confined Masonry Structures as Seismic Resistant Structure

Journal of emerging technologies and innovative research, 2020

Seismic force is a major concern for the engineers nowadays specially in countries like India where occurrence of earthquakes are frequent nowadays. In order to make a structure seismic resistant, engineers opt for ductile design, ductile detailing, shear wall construction, etc. which ultimately sometimes increase the cost for small and medium height structures. Confined Masonry are those structures which are mainly build with walls but are confined with beams and columns which are poured after the walls are built. For Medium and Low height structures, this Confined Masonry structures gives a good performance against seismic forces and hence can be used as a Seismic Resistant Structures economically. This paper mainly deals with the Overview of Confined Masonry Structures, their differences with RC structures and some basic guidelines for construction of Confined Masonry Structures which are collected from various research papers and books. It also highlights various analysis techni...

Numerical investigations on the seismic behaviour of confined masonry walls

In the last century, severe earthquakes highlighted the seismic vulnerability of unreinforced masonry buildings. Many technological innovations have been introduced in time in order to improve resistance, ductility, and dissipation properties of this type of constructions. The most widely diffused are reinforced masonry and confined masonry. Damage observation of recent earthquakes demonstrated the effectiveness of the response of confined masonry structures to seismic actions. In general, in this type of structures, reinforced concrete beams and columns are not main structural elements, however, they have the following functions: to confine masonry in order to increase its ductility; to bear tensile stresses derived from bending; to contrast the out-of-plane overturning of masonry panels. It is well evident that these functions are as much effectively performed as the connection between masonry and reinforced concrete elements is good (for example by mean of local interlocking or reinforcements). Confined masonry structures have been extensively studied in the last decades both from a theoretical point of view and by experimental tests Aims of this paper is to give a contribution to the understanding of the seismic behaviour of confined masonry walls by means of numerical parametrical analyses. There latter are performed by mean of the finite element method; a nonlinear anisotropic constitutive law recently developed for masonry is adopted. Comparison with available experimental results are carried out in order to validate the results. A comparison between the resistance obtained from the numerical analyses and the prevision provided by simplified resistance criteria proposed in literature and in codes is finally provided.

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.

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.

Performance of masonry enclosure walls: lessons learned from recent earthquakes

Earthquake Engineering and Engineering Vibration, 2012

This paper discusses the issue of performance requirements and construction criteria for masonry enclosure and infi ll walls. Vertical building enclosures in European countries are very often constituted by non-load-bearing masonry walls, using horizontally perforated clay bricks. These walls are generally supported and confi ned by a reinforced concrete frame structure of columns and beams/slabs. Since these walls are commonly considered to be nonstructural elements and their infl uence on the structural response is ignored, their consideration in the design of structures as well as their connection to the adjacent structural elements is frequently negligent or insuffi ciently detailed. As a consequence, nonstructural elements, as for wall enclosures, are relatively sensitive to drift and acceleration demands when buildings are subjected to seismic actions. Many international standards and technical documents stress the need for design acceptability criteria for nonstructural elements, however they do not specifi cally indicate how to prevent collapse and severe cracking, and how to enhance the overall stability in the case of moderate to high seismic loading. Furthermore, a review of appropriate measures to improve enclosure wall performance and both in-plane and out-of-plane integrity under seismic actions is addressed.