1. PhD student, Department of Civil & Environmental Engineering, University of Auckland, Auckland, New Zealand, hder004@aucklanduni.ac.nz
2. Associate Professor, Department of Civil & Environmental Engineering, University of Auckland, Auckland, New Zealand, j.ingham@auckland.ac.nz
3. Associate Professor, School of Civil, Environmental and Mining Engineering, University of Adelaide, Australia, mcgrif@civeng.adelaide.edu.au

ABSTRACT

Behaviour of full-scale unreinforced masonry (URM) walls subjected to out-of-plane uniform loads was investigated by testing three brick walls. Uniform loading was applied on the surface of the walls using a system of airbags. The walls, having a constant width of 1200 mm, had a height varying from 2000 mm to 4100 mm. The walls were two-leaf thick and had slenderness ratios of 9, 16 and 19. All of the tests were performed using simply supported boundary condition, and test specimens behaved as ideal one-way bending elements. Tri-linear forcedisplacement models were constructed based on the experimental curves recorded during the testing. It was found that the wall geometry and axial load influenced the shape of the models. General recommendations were made for tri-linear modelling of out-of-plane URM walls based on this finding.

KEYWORDS: out-of-plane, unreinforced masonry wall, force-displacement curve, tri-linear model, airbag testing

C8-4

1. PhD Student, Department of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK, cen1s3m@leeds.ac.uk
2. Senior Lecturer, Department of Civil Engineering, University of Leeds, Leeds, LS2 9JT, UK, j.p.forth@leeds.ac.uk

ABSTRACT

The mechanical behaviour of un-reinforced masonry walls subject to quasi-static and dynamic loading is difficult to assess in practice due to a) the inherent unpredictability and variability associated with the performance of the bricks and the mortar both individually and as a composite material b) the difficulty of correctly identifying the boundary conditions and reproducing these under laboratory conditions. Recently, a more ‘basic’ retrofitting technique that involves building a second masonry panel, parallel to an existing one (i.e. collar-jointed masonry), in order to enhance the behaviour of the existing wall has been trialled in certain real structures. The new leaf is tied to the old panel by means of the collar joint and/or by steel ties.

To assess this practical approach, tests were performed on three different arrangements, namely 1) collar joint without ties, 2) collar joint with ties and 3) ties without a collar joint; all walls were subject to quasi-static loading. The aim was to evaluate the shear capacity of the bond between the two panels, to assess the suitability of such a technique and to establish whether or not there is a need for ties in conjunction with a collar joint. This paper describes the development of a laboratory testing rig which can be used to accurately assess these criteria. Preliminary results illustrate that the test setup to represent the real life situation has been identified and gives consistent results. Also, the use of steel ties with a completely filled collar joint seems to be unnecessary.

KEYWORDS: collar jointed masonry, ties, shear capacity

C8-3

¹ College of Civil Engineering, Nanjing University of Technology, China, Email: zhgguo@163.com

ABSTRACT

The problem of the restraint on the beam end from walls for structural masonry buildings with Reinforced Concrete floors has been examined. An experimental study of the restraint on the beam end is described in this paper. The test model is a two-story, one-span masonry structure. The restraint on the beam end, the failure process and failure mode, and the variation in restraining moment and the angle of rotation on the beam were studied. The moment and deflection at the span center were analyzed, and compared with calculated values according to the building code. At the same time, a finite element method (FEM) analysis for evaluating the load deformation process was presented. The restraint due to the nature of the joint, the embedment length of the beam in the wall and the stress on the wall were all studied and were discussed. The effect on the beam restraining moment from increasing the axial stress on the upper wall was obtained. The analytical and experimental results also indicate that a restraining moment exists on the beam end, and that this moment varies with increasing load. The restraining moment on the beam was shown to be affected by the beam stiffness, masonry stiffness, the embedment length of beam in the wall, axial load on the wall, and the nature of the connection of the beam to the wall.

KEYWORDS: composites structure; restraint on the beam end; finite element analysis

B8-4

Associated Professor, Section Structural Masonry, Department of architecture, building and planning, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands, a.t.vermeltfoort@tue.nl

ABSTRACT

This paper describes research into the behaviour of so-called “composite lintels” i.e. load bearing masonry in combination with prefabricated concrete lintels. Eighteen identical walls were loaded in plane to rupture. Nine layers of stretcher bond masonry, 562.5 mm in height, were built on prefab concrete lintels (60×100 mm²) with a span of 2800 mm. The effects of two types of supports and two types of loading on the mechanical behaviour of in plane loaded composite lintels were studied. Roller supports were simulated by suspending steel blocks from the roof beam of the test frame. A support condition, often used in practice, was simulated by a layer of felt on a brick. Two series of six walls were symmetrically loaded at four points. A third series of six walls were asymmetrically loaded at one point. The mean failure shear load for the four point loading condition was V_fail = 31 kN. For the one point condition it was V_fail = 24.4 kN. On average, the ultimate load (F_ult) was 15% higher than the failure load (F_fail). Supported on rollers, three walls failed in the constant moment area (mid span). The fifteen other walls failed in the maximum shear load area near the supports. The height of the compression zone at mid span depended on the support condition and was largest for the felt support condition, where horizontal movement of the lintel was restrained. The support condition (rollers or felt) had a negligible effect on the load bearing capacity.

KEYWORDS: Composite lintel, support, shear, strength variation, load bearing masonry

B8-2

1. Associate Professor, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India, dcrai@iitk.ac.in
2. Graduate Student, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India, komaraneni1984@gmail.com
3. D. Student, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, UP 208016, India, singhal@iitk.ac.in

ABSTRACT

Half-scaled clay brick infill masonry panels were subjected to a sequence of slow cyclic in-plane drifts and shake table generated out-of-plane ground motions to assess the interaction of in-plane damage over the out-of-plane behaviour. The results show that the infill panels maintained structural integrity and out-of-plane stability even when severely damaged; and out-of-plane failure may not be because of excessive inertial forces only but can be due to large out-of-plane deflections. Also, the weaker interior grid elements which divide the masonry in smaller subpanels were able to delay the failure by controlling out-of-plane deflection and significantly enhancing in-plane response.

KEYWORDS: Masonry, infills, stability, seismic response

A8-2

1. Professor, Faculty of Built Environment & Engineering, Queensland University of Technology, Brisbane, Australia. Ph. +61 7 3138 6666; email: m.dhanasekar@qut.edu.au
2. Assistant Professor, Department of Structural & Transportation Engineering, University of Padova, Padova, Italy. Ph. +39 49 8275631; email: daporto@dic.unipd.it

ABSTRACT

Thin bed technology for clay/ concrete masonry is gaining popularity in many parts of the developed economy in recent times through active engagement of the industry with the academia. One of the main drivers for the development of thin bed technology is the progressive contraction of the professional brick and block laying workforce as the younger generation is not attracted towards this profession due to the general perception of the society towards manual work as being outdated in the modern digital economy. This situation has led to soaring cost of skilled labour associated with the general delay in completion of construction activities in recent times. In parallel, the advent of manufacturing technologies in producing bricks and blocks with adherence to specified dimensions and shapes and several rapid setting binders are other factors that have contributed to the development of thin bed technology. Although this technology is still emerging, especially for applications to earthquake prone regions, field applications are reported in Germany for over a few decades and in Italy since early 2000. The Australian concrete masonry industry has recently taken keen interest in pursuing research with a view to developing this technology. This paper presents the background information including review of literature and pilot studies that have been carried out to enable planning of the development of thin bed technology. The paper concludes with recommendations for future research.

KEYWORDS: Structural Masonry; Thin Bed Joints; Failure Mechanisms; Interface; Ductility.

B7-3

¹Managing Director, NNC Consultant Pvt. Ltd., B-2, Jaswant Chambers, Okhla, Jamia Nagar, New Delhi-110025, India.

²Professor, Civil Engg. Department, Indian Institute of Technology, Delhi, New Delhi-110016, India.

ABSTRACT

A series of laboratory tests has been conducted to investigate the influence of bed joint orientation on interlocking grouted stabilised sand-flyash brick masonry under cyclic compressive loading. Five cases of loading at 0⁰, 22.5⁰, 45⁰, 67.5⁰ and 90⁰ with the bed joints are considered. The brick units and masonry system developed by Prof. S.N. Sinha is used in present investigation. Eighteen specimens of size 500 mm x 100 mm x 700 mm (19.68 in. x 3.94 in. x 27.55 in.) and twenty seven specimens of size 500 mm x 100 mm x 500 mm (19.68 in. x 3.94 in. x 19.68 in.) are tested. The loops of stress-strain hysterisis obtained from cyclic loading tests have been used to determine the energy dissipation characteristics of interlocking grouted stabilised sand-flyash brick masonry. The variation of envelope strain, common point strain and stability point strain with plastic strain has been plotted. A polynomial formulation is proposed for the relations between energy dissipation ratio versus envelope strain and energy dissipation ratio versus residual strain. These relations indicates that the decay of masonry strength starts at about 0.42 to 0.75 times of peak stress depending upon the load case.

KEYWORDS: Interlocking brick, grout, uniaxial, cyclic loading, envelope curve, common point, stability point, stress-strain hysteresis

B6-2

1. Assistant Professor, Department of Structural Engineering, Politecnico di Milano, Italy, cardani@stru.polimi.it
2. Full Professor, Department of Structural Engineering, Politecnico di Milano, Italy, binda@stru.polimi.it
3. Assistant Professor, Department of Structural Engineering, Politecnico di Milano, Italy, condoleo@stru.polimi.it
4. Associate Professor, Department of Structural Engineering, Politecnico di Milano, Italy, anzani@stru.polimi.it

ABSTRACT

An experimental investigation aimed to the evaluation of the state of damage of historic brick masonry structure, referred to as The Bellevue Tower, is presented. The tower was built at the beginning of the 16^th century as part of the Ferrero Palace-Masserano-La Marmora, on the highest part of Biella, in the Italian region of Piedmont, and became the city landmark. The tower has a square plan for the first three lower floors from the ground level and an octagonal plan for the remaining four floors, ending with a stone-decorated cantilevered crowning.

The tower was a part of a public Palace from which it was separated, in terms of property, at the beginning of the 20^th century. This separation altered the use and conservation path of the tower, that nowadays suffers from a severe state of damage and requires an immediate intervention and rehabilitation of the masonry structures and overhanging elements for safety reasons.

A methodology is put forward for combining laboratory and non-destructive testing methods with a monitoring system in order to evaluate the potential for conservation of this historic tower and its sustainability, in view of an effective intervention design.

KEYWORDS: brick masonry, flat jack test, monitoring, NDT, tower

C5-3

Emeritus Professor of Building Engineering, School of Architecture and the Built Environment, The Royal Institute of Technology (KTH), Stockholm, Sweden; bogoran@arch.kth.se

ABSTRACT

Masonry was the most common material used in construction in ubran areas in Sweden for a long time. It was not until the 1920s that reinforced concrete became widely used. A combination of materials became common in multi-family housing and, in some cases, also in single-family housing; floor slabs were made of concrete, walls were made of brick masonry and roof structures were constructed of wood. A late example of such houses has been the topic of the author’s recent technical contribution in rebuilding economical structures for modern living. The project serves as an example of modernizing with a sense of proportion. The house is a twostorey structure constructed between 1959 and 1961, by the Swedish architect Folke Hedérus, “the most talented architect of his generation”. The house, situated on Lidingö, an insular community close to Stockholm, has a living area of some 300 m². The roof, originally being flat, its edges are now lifted from 140 to 340 mm to allow for an increase of mineral wool insulation, and have an inward inclination towards a runway with only two outlets (originally three). The vertical storm water piping was increased from 120 to 150 mm for compensation. The large thin glasses windows of the façade are replaced by modern glass panes, lowering the heat transmission factor from 2.6 to 1.1 W/m² K. The insulation of wooden parts of the second floor is doubled from 100 to 200 mm of mineral wool. The concrete floor of the lower storey, originally un-insulated, was covered with 100 mm cellular plastic, glued upwards. Brick walls were however not modified. In total, the heat losses from the vertical parts were halved. In addition, and most important, the ventilation and heating systems were separated by replacing circulating hot air with water circuits on each floor.

KEYWORDS: brick masonry, floor heating, heat insulation, rehabilitation, slopes

B5-5

1. Structural Engineer, Bechtel National, Inc., San Francisco, California, skadysie@msn.com
2. Professor and Vice Chair, 733 Davis Hall, Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720-1710, mosalam@ce.berkeley.edu

ABSTRACT

This paper describes a practical analytical model which can be used for the seismic evaluation of unreinforced masonry (URM) infill walls located within a reinforced concrete (RC) frame. The model, consisting of diagonal beam-column members utilizing fiber-element cross sections, is suitable for use in nonlinear time history analyses. The model considers both the in-plane (IP) and the out-of-plane (OOP) responses of the infill, as well as any chosen convex interaction between IP and OOP capacities. The behaviour is elastoplastic, and limit states may be defined by deformations or ductilities in the two directions. These limit states may be chosen to conform to code guidelines or they may be developed independently by the engineer. The model is composed of elements available in commonly used structural analysis software programs. The performance of the model is shown to be satisfactory for static pushover and dynamic analyses using a single panel structure. The proposed infill model is incorporated into a five-storey RC moment frame building with URM infill walls. It is subjected to 20 sets of ground acceleration time histories at five different levels of spectral acceleration. Collapse of the infill panel is assumed to occur at critical displacement ductilities in the IP and OOP directions with interaction between the ductilities considered. Fragility functions, giving the probability of collapse as a function of spectral acceleration level, are calculated and discussed.

KEYWORDS: earthquake, fragility, infill, in-plane, out-of-plane, model

C4-3