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. Wembley Innovation Ltd, Atlas Road, Wembley, Middlesex, HA9 0JH, United Kingdom, hamish.corbett@wembleyinnovation.co.uk
2. CERAM, Queens Road, Penkhull, Stoke-on-Trent, Staffordshire, United Kingdom, geoff.edgell@ceram.com

ABSTRACT

In 2006 CERAM began an experimental programme to investigate the performance of large blockwork walls, reinforced at intervals up their height by bond beams[1]. The concept was developed by Wembley Innovation as a simple alternative to the use of wind posts. The performance of the walls was very encouraging and lateral loads in the region of 6kN/m² were satisfactorily resisted. Since the initial tests various configurations of the walls, for example wall height to length ratios have been varied, the introduction of windows and door openings have been investigated and the connections to the framing elements of the building have been refined. In order to introduce the system to the mainstream of structural engineering consultants in the UK and elsewhere CERAM produced a design procedure which has been developed in conjunction with consultants Jenkins and Potter and Buro Happold. The procedure essentially builds upon the approach in the UK for the design of walls containing prefabricated bed joint reinforcement and incorporated in BS 5628: Part 1. As current UK Codes of Practice[2] are due to be withdrawn in 2010 and the inclusion of new material in the Eurocode (EN 1996-1-1, Eurocode 6)[3] is not yet possible CERAM as an independent body has published a Design Guide[4] for the system. This paper introduces the guide, explains the provisions and shares the supporting test evidence. The system has been used on a number of major schemes and some feedback on the experience so far is given.

KEYWORDS: Aggregate concrete blockwork, lateral load design, bond beams

A8-5

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. 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

¹ Former Master Student, ² Professor ,

Department of Civil Engineering, Federal University of Sao Carlos, BRAZIL, parsekian@ufscar.br

ABSTRACT

The widespread use of precast façade panels expedites constructions and increases their quality. Using such elements enables the construction process to be conducted on industrial scale. This paper reports on a study of clay block prestressed masonry panels as an alternative for the commonly prestressed or reinforced concrete façade panels. The panel was designed to bear regular winds loads and also tested for construction and transportation loads such as self-weight. The construction process was tested in two modes. First, several small vertical panels were built, after which they were rotated to the horizontal position and joined together by prestressed cables, forming a single 5-m long horizontal panel. In the second mode, the whole panel was built and prestressed horizontally. The two complete panels were then subjected to lateral loads in order to determine the failure load and displacements. The conclusions drawn from the tests were that both panels were able to bear loads close to predicted. Also both panels are expected to resist designing load in most practical cases

KEYWORDS: prefabrication; prestressed masonry; design

B2-5