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. Associate Professor, College of Architecture, Georgia Institute of Technology, Atlanta, Georgia, USA, russell.gentry@coa.gatech.edu
2. Doctoral Candidate, College of Architecture, Georgia Institute of Technology, Atlanta, Georgia, USA, andres.cavieres@gatech.edu
3. Visiting Assistant Professor, College of Architecture, Georgia Institute of Technology, Atlanta, Georgia, USA, tristan.al-haddad@arch.gatech.edu

ABSTRACT

This paper, explores the extent to which concepts of parametric modeling can be applied to support the design process of load-bearing masonry buildings. The research uses the concepts of building information modeling and parametric representation to capture and execute relevant constructive knowledge for the design of doubly-curved masonry walls. Prototype software has been developed to translate this knowledge into a set of explicit parametric rules and geometric constraints which “bound” the curvatures of the masonry walls to those with admissible construction and structural solutions. Rules for calculation of vertical and horizontal reinforcement placement of rebar in grouted cells and bond beams have been developed to allow for preliminary design of doubly-curved walls. The software operates within a CAD environment and provides real-time feedback on wall configuration and reinforcement as the model is built. The paper reviews the rules necessary for block wall description, including door and window openings, and focuses on the calculations necessary for preliminary structural design of doubly-curved load-bearing masonry walls.

KEYWORDS: building information modeling, parametric modeling, concrete masonry units

C8-2

1. Professor Emeritus, Centre for Effective Design of Structures, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, drysdale@mcmaster.ca
2. A.Sc. Candidate Department of Civil Engineering, McMaster University, hughekj@mcmaster.ca
3. A.Sc. Candidate Department of Civil Engineering, McMaster University, wierzbj@mcmaster.ca
4. A.Sc. Candidate Department of Civil Engineering, McMaster University, bantinbr@mcmaster.ca
5. Martini Mascarin and George Chair in Masonry Design, Centre for Effective Design of Structures, Department of Civil Engineering, McMaster University, eldak@mcmaster.ca

ABSTRACT

This paper reports on full scale laboratory tests of concrete block walls reinforced with surface mounted ties to create a tied arch structural system. The intent is to use this system in basement wall construction so that hollow 20cm concrete block can be used in a cost-effective manner. Ten tests were performed on 3m high walls to investigate use of various reinforcing tie cross sections and various methods of anchoring the ties at the top and bottom of the wall to develop the tie strength. Although choice of an economical tie design was found to be important, it was readily apparent that development of simple anchoring systems would have the greatest impact on both cost and marketing success. Forty-six tests of various methods of anchoring the ties were carried out. The results of the wall and anchorage tests provide proof of the structural concept and form the basis for seeking code approval for use of arching concrete block basement walls.

KEYWORDS: Arching, backfill, basements, bending, concrete block, reinforcing, soil pressure, tied arch, ties.

C7-4

1. Engineer, OPUS Architects & Engineers, Minnetonka, MN 55343, USA, jennifer.popehn@opus-ae.com
2. Professor, Dept. of Civil Engineering, Univ. of Minnesota, Minneapolis, MN 55455, USA, schul088@umn.edu
3. Prof., Dept. of Civil & Architectural Engineering, Univ. of Wyoming, Laramie, WY 82071, USA tannerj@uwyo.edu

ABSTRACT

The buckling strength and deformation capacity of an unreinforced masonry wall (URM) can be significantly affected by both initial imperfections and axial load eccentricity. To account for this decrease in strength, the 2008 TMS-402 (i.e., United States (US) masonry design provisions) Strength Design chapter includes a new provision for including second order effects through a moment magnifier. However, this method of treatment has limitations: initial imperfections are essentially not considered when the eccentricity is larger than 10% of the wall thickness. Additionally, when designing using Allowable Stress Design (ASD), the second order bending effects arising from axial load are ignored. To determine the accuracy of the ASD and SD provisions, the calculated moment magnifiers were compared to experimental data from seven slender URM wall tests conducted at the University of Minnesota. In the experimental study, three of the walls were constructed of cored clay brick, while the remaining four were fabricated using hollow concrete block. The simply-supported masonry wall tests began with a pre-selected axial load which was applied to the walls in force control using two vertical load actuators and held constant throughout the tests. After the axial load was applied to the walls, lateral load was applied with a whiffletree system operated in displacement control. The lateral displacement was increased until all lateral load capacity had diminished.

KEYWORDS: slenderness, imperfection, second order, axial load eccentricity, unreinforced masonry, buckling strength

C8-1

1. Professor Emeritus, Centre for Effective Design of Structures, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, drysdale@mcmaster.ca
2. A.Sc. Candidate Department of Civil Engineering, McMaster University, wierzbj@mcmaster.ca
3. A.Sc. Candidate Department of Civil Engineering, McMaster University, hughekj@mcmaster.ca
4. A.Sc. Candidate Department of Civil Engineering, McMaster University, bantinbr@mcmaster.ca
5. Martini Mascarin and George Chair in Masonry Design, Centre for Effective Design of Structures, Department of Civil Engineering, McMaster University, eldak@mcmaster.ca

ABSTRACT

In modern house construction, the use of increased head room and the trend toward greater depths of backfill have led to reduced use of concrete block in basement construction. This paper provides conceptual information on use of 20 cm concrete block basement walls fitted with external surface mounted ties anchored into the top and bottom of the wall to create tied arch action. Test results verify that this structural system works well. It also provides a cost efficient alternative to existing basement wall construction systems with minimal changes to traditional construction techniques.

KEYWORDS: arching, backfill, basements, bending, concrete block, reinforcing, soil pressure, tied arch, ties.

C7-3

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

^1,2 University of Windsor, Windsor, ON, N9B 3P4, Canada

³ Canada Masonry Design Centre, Mississauga, ON, L5T 2N7, Canada

ABSTRACT

The current Canadian standard recommends strength reduction factors of 0.5 and 0.7 when compressive force is applied normal to the head face (parallel to the bed face). This strength reduction factor value is 0.7 if the grout is horizontally continuous (when there is no web interruption in the grout) and it is 0.5 if the grout is not horizontally continuous (when web interruption exists). It is argued that the reduction factors (0.5 and 0.7) suggested in the Canadian standard is highly conservative and is not based on any detailed study. Thus, a detailed research program based on experimental study on prism specimens with three levels of grout interruption was undertaken. The prism specimens were loaded in two different directions: (i) parallel to the bed face and (ii) perpendicular to the bed face. Varying degrees of web interruption were incorporated in the prism specimens to investigate the effects of various levels of web interruption on the compressive strength when loaded normal to the head face. This paper discusses the test specimens and test methods used and the results obtained from the study.

KEYWORDS: masonry prism specimens, loading parallel to bed face, grout interruption, strength reduction factor

B8-3

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. Professor, Department of Engineering, Pontifical Catholic University of Peru, Av. Universitaria 1801, Lima 32, Peru, dquiun@pucp.edu.pe
2. Professor, Department of Engineering, Pontifical Catholic University of Peru, Av. Universitaria 1801, Lima 32, Peru, asanbar@pucp.edu.pe
3. Associate Professor, Department of Engineering, Pontifical Catholic University of Peru, Av. Universitaria 1801, Lima 32, Peru, wsilva@pucp.edu.pe

ABSTRACT

Brick masonry is widely used in Peru for walls in many low rise buildings, such as dwellings, offices, schools, and alike. Also, partition walls in medium and high-rise buildings are made usually of brick or block masonry. The design and construction of such walls is regulated by the Peruvian Masonry Code issued in 2006. However, technical literature in masonry is still quite limited, and significant efforts are needed to teach seismic structural design and construction practices correctly.

In Peru, the courses of structural masonry for civil engineers students are limited to a few universities. The Pontifical Catholic University of Peru (PUCP) has developed most of the experimental research in masonry in Peru, and offers such courses in undergraduate and graduate level, in the classical way of lectures in classrooms and laboratory tests.

A relatively new approach to disseminate knowledge in this field is the use of virtual environment. The blog of masonry (http://blog.pucp.edu.pe/albanileria in Spanish) developed by Angel San Bartolomé has passed its first year offering a new way to communicate recent research reports to masonry users all over Peru and beyond. Nowadays, the graduate course is being offered for the first time in a virtual way for master students and it looks as a promising virtual course for students in Peru and other Latin American countries.

KEYWORDS: teaching, education, blog, masonry, virtual education, Internet

C7-2