Bowen Zeng,  and Yong Li

Bowen Zeng, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada., bzeng1@ualberta.ca
Yong Li, Assistant Professor, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada., yong9@ualberta.ca

ABSTRACT
Detailed finite element modeling of masonry structures is essential to understand their complex mechanical behavior accounting for different failure mechanisms, which highly depends on the mortar joints (i.e., mortar layer and unit-mortar interaction). As such, this study presents a plasticity-based constitutive model for a 3D interface element that is capable of capturing various failure modes of mortar joints, including tension cracking, shear sliding, and compressive crushing. It is characterized by two hyperbolic yield surface criteria: tension-shear failure surface and compressive cap surface. The evolutions of the yield surfaces and state variables are formulated based on the concept of strain-softening/hardening. A fully implicit Euler Backward integration algorithm, combined with a local-global Newton-Raphson (NR) solver, is adopted to achieve the predictor-corrector returning mapping procedure in the numerical formulation. Additionally, the variations of dilatancy and fracture energy are introduced, aiming to describe the mechanical behavior of mortar joints accurately. The model is implemented in the finite element software Abaqus via UMAT. The proposed interface model is validated with the unit-mortar-unit assemblages and unreinforced masonry walls. The capability of newly developed interface model shows its potential to be used to further explore the mechanical behavior of masonry structures.

KEYWORDS: finite element modeling, interface element, implicit integration algorithm, masonry structures

Soraya Roosta and Yi Liu

Soraya Roosta, PhD Candidate, Department of Civil and Resource Engineering, Dalhousie University, Halifax, NS, Canada, Soraya.roosta@dal.ca
Yi Liu, Professor, Department of Civil and Resource Engineering, Dalhousie University, Halifax, NS, Canada, Yi.liu@dal.ca

ABSTRACT
This paper presents the development of a finite element model in OpenSees to simulate the behaviour of all-masonry infilled frames subjected to lateral loading. All-masonry infilled frames
refer to an infilled frame system where both the bounding frame and the infill panel are made of concrete masonry units. While masonry columns and beams can be constructed from large
masonry boundary element units and are reinforced and fully grouted, the infill panel can be constructed with standard concrete masonry units with no reinforcement and grouting. The finite element model developed in this study is a macro-model consisting of multi-strut and special shear springs to consider the compressive and shear failure of the infill and its effect exerted on the
bounding frame. The validation of the model, conducted through the comparison of experimental and numerical load vs. displacement responses and failure modes, showed that the proposed model is capable of providing accurate simulation results including the post-ultimate behaviour. The comparison between the proposed and other macro-models in the available literature showed that the proposed model performed better in providing estimates in stiffness, strength, and load vs. deflection responses.

KEYWORDS: concrete masonry infills, masonry frames, finite element study, macro-model, shear spring, multi-strut

Neil Cox, Nicholas Huttemann and Spencer Cox

Neil Cox, CEO, SoundQA Solutions Inc, 6158 Elgin Avenue, Burnaby BC V5H 3S4, neil.cox@soundqa.com
Nicholas Huttemann, Product Engineer, SoundQA Solutions Inc, 6158 Elgin Avenue, Burnaby BC, nick.huttemann@soundqa.com
Spencer Cox, Co-Founder, SoundQA Solutions Inc, 6158 Elgin Avenue, Burnaby BC V5H 3S4, spencer.cox@soundqa.com

ABSTRACT
This paper presents preliminary evaluation results and refinements for a new non-destructive method of estimating the strength of concrete masonry and related units using acoustics. The
method provides fast, simple, non-destructive, and economical strength testing. Usage involves gently striking the unit with a pendulum and analyzing the resulting acoustic impulse response. Results are produced immediately. Results are presented for a study conducted in cooperation of the NCMA testing lab, where the method was applied along with standard testing for more than 100 ASTM C140 testing projects. Results for 59 projects involving testing of 20cm concrete masonry units are presented. The method was shown to be extraordinarily repeatable, and a strong correlation with estimates of compressive strength obtained through compression testing was demonstrated. There is also evidence that the method is more precise than compression testing. These results, combined with its simplicity and ease of use, support introduction of the method to complement existing testing methods in concrete quality assurance programs.

KEYWORDS: acoustics, concrete, masonry, NDT, non-destructive, strength, testing

Nathanaël Savalle, Elham Mousavian, Carla Colombo and Paulo B. Lourenço

Nathanaël Savalle, PhD, University of Minho, University of Minho, ISISE, Department of Civil Engineering, Guimarães, Portugal, n.savalle@civil.uminho.pt
Elham Mousavian,PhD, Department of Structures for Engineering and Architecture, University of Naples Federico II, Italy, elham.mousavian@unina.it
Carla Colombo, PhD Student, University of Minho, University of Minho, ISISE, Department of Civil Engineering, Guimarães, Portugal, carla.colombo95@gmail.com
Paulo B. Lourenço, Full Professor, University of Minho, University of Minho, ISISE, Department of Civil Engineering, Guimarães, Portugal, pbl@civil.uminho.pt

ABSTRACT
Modelling masonry bond pattern is still challenging for the scientific community. Though advanced Laser Scanning methods are available and allow to extract blocks sizes and shapes of
actual masonry structures, they are up to now very time-consuming and complex to set up. Therefore, modelling masonry as an ideal and regular assemblage of regular units is still very common in the scientific field. This paper presents a generative algorithm for masonry specimens built with a single-leaf cond pattern. It is based on C# programming under the environment offered by Rhinoceros (+ Grasshopper). Five components have been constructed (wall, corner, T and cross-connections, and opening). They can be assembled, up to infinity, to build complex masonry specimens. Moreover, they are all parametrised to account for every wish of the modeller. The global methodology is found highly time-efficient, with the creation of an initial geometry composed of 5 – 10 components requiring around 10 minutes and, while the update due to a parameter variation is done in less than one second. The paper finally discusses the next developments of the promising generative algorithm.

KEYWORDS: masonry, parametric modelling, c# coding, single-leaf, grasshopper

John M Nichols

John M Nichols, Associate Professor, Construction Science Department, Texas A&M University, College Station, TX, 77843-3139 jm-nichols@tamu.edu

ABSTRACT
Masonry is a culturally preferred building product in Indonesia and Italy. The use of culturally preferred products, can often lead to interesting challenges in minimizing the loss of life in building collapse in earthquakes. A culturally preferred building product is one that has widespread local acceptance, such as clay roofing tiles in Newcastle, Australia, which often limit the use of other
products, from cultural resistance to change. This problem of discussing culturally preferred building product is faced by researchers who look at causes for deaths in earthquakes and who seek to fairly comment on material use, but need to be aware of cultural sensitivities. This paper outlines in a first stage, a statistical analysis of the distribution of deaths in two fatal earthquakes,
the 2016 Central Italy and 2006 Jogjakarta events. The two earthquakes are amongst a small category of highly fatal earthquakes for the earthquake magnitude. The highly fatal earthquakes provide an upper bound to likely human losses and human loss rates. The paper compares the results to previous statistical studies of other fatal earthquakes for calibration purposes. The second stage is to consider the impact of a culturally preferred building product on the human losses. As a standard method of analysis, the statistical procedures consider the change in the fatality loss rate with distance and the spatial variations in the rates of loss. The results are entirely consistent with earlier results determined for other fatal events. The findings point to a change in the rate of loss with distance and geographic features, such as river banks or mountains or fault orientation or the use of a preferred building product. The rate of human loss is neither linear or squared, but
somewhere in between these extremes. The mathematical results are useful for estimating potential losses in future theoretical earthquakes and for considering the ethical questions as to the use of publicly preferred building products. The events provide a window in the impact of publicly  preferred building products and highlight some of the interesting ethical issues in construction.

KEYWORDS: human, losses, masonry, public preference, loss rate, Indonesia, Italy

Matthew East, Mohamed Ezzeldin, and Lydell Wiebe

Matthew East, PhD Candidate, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, eastma@mcmaster.ca
Mohamed Ezzeldin, Assistant Professor, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, ezzeldms@mcmaster.ca
Lydell Wiebe, Associate Professor, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, wiebel@mcmaster.ca

ABSTRACT
Steel flexural yielding arms can be an effective energy dissipation device for controlled rocking masonry walls. In controlled rocking masonry walls, uplift of the wall from the foundation is
allowed in a way that can localize damage to externally mounted energy dissipation devices and subsequently minimize post-earthquake residual drifts. Recent testing at McMaster University investigated the ability of steel flexural yielding arms to serve as easily replaceable energy dissipation devices with the ability to simultaneously resist sliding demands. Based on this previous testing, the current study investigates how to capture the behaviour of such devices through a finite element model using OpenSees, with the purpose of integrating the component models of flexural yielding arms with models of controlled rocking masonry walls. The flexural arm modelling approach is validated against the experimental data in terms of material data from coupon tests and low cycle fatigue parameters based on the observed hysteretic response from the experiments. The developed model is then used to investigate the performance of a wide array of devices, beyond the initial series of tests. The results showed that the proposed design equations are accurate within the examined geometric configurations.

KEYWORDS: seismic design, controlled rocking, reinforced masonry, energy dissipation device, numerical modelling

Bennett Banting

Bennett Banting, Director of Technical Services, Canada Masonry Design Centre, 360 Superior Blvd., Mississauga, ON, Canada, Bbanting@canadamasonrycentre.com

ABSTRACT
Design for earthquake forces in Canada underwent major changes at both the national model building code and masonry design standard levels from 2004 to 2014. The most recent edition of
the CSA S304 Design of Masonry Structures published in 2014 introduced a new section: Clause 16 Special provisions for seismic design. One of the technical additions to the standard was a limit to the design level of axial load for Conventional Construction shear walls for buildings that possess with a moderate seismic hazard (IEFaSa(0.2) ≥ 0.35). A maximum axial compressive stress of not more than 0.1fʹm under seismic load cases is permitted. It is well understood that flexurally governed shear walls possess a greater level of inelastic energy dissipation when axial loads are low. In seismic design, it is generally preferable to have a small ratio of the depth of neutral axis, c, to the length of the wall, ℓw, to ensure inelastic yielding of flexural reinforcement. Although seismic response is likely enhanced by restricting axial loads to the required level, the proposed limit has shown itself to be difficult to meet within typical multi-storey loadbearing masonry raising concerns from the design community about its application. It can also be observed that the current limit is often more restrictive than what one could calculate using rational calculations or the limits for c/ℓw adopted by comparable walls systems in reinforced concrete and masonry design in the U.S. In lieu of the axial load limit of 0.1fʹm, a designer is permitted by CSA S304 to carryout a more comprehensive analysis, the basis of which is not defined by the standard. The following paper provides a rational means to meet the more comprehensive analysis requirements of the CSA S304 in order to design conventional construction shear walls with axial load levels that are over 0.1fʹm.

KEYWORDS: CSA S304, conventional construction, seismic design, shear walls

Bradley Crumb

Bradley Crumb, Engineering Technical Resources, Canada Masonry Design Centre, 360 Superior Blvd., Mississauga, ON, Canada, Bcrumb@canadamasonrycentre.com

ABSTRACT
In the process of updating the masonry design software Masonry Analysis Structural Systems (MASS) to include the added scope of the seismic design in Clause 16 of CSA S304-14, several technical issues arose related to performing and satisfying the ductility verification for moderately ductile and ductile shear walls. To deal with the prohibitively long calculation times associated with repeating ductility verification attempts for each failing cross section, a methodology was developed to allow the software to design shear walls that satisfy the ductility verification. For cases where increasing compressive strain is not an available option for a shear wall cross section, the software determines a target neutral axis depth to compare for future design iterations. Following this, MASS increments cross sectional properties and compares the neutral axis depth to reach the saved target value. Alternately, a failure message is displayed if the target value can not be reached within the user defined cross-section parameters. In the case of shear walls containing boundary elements that initially fail a ductility verification attempt, it is possible for the maximum compressive strain to be increased to improve ductility without changing cross sectional geometric or material properties. The software first determines the required increase in compressive strain that must be achieved, before comparing that value to other potential limiting factors. These factors include code minimums and maximums, strain within the shear wall web, confinement from ties within the boundary element, and the interaction of any strain increase with neutral axis depth. This methodology is valuable for addressing ductility verification failures by reducing the number of ductility verification iterations from the tens of thousands down to single digits, making substantial improvements in calculation times and more easily allowing engineers  to find workable designs. Additional recommendations are made for designers to consider that fall beyond the scope of the software.

KEYWORDS: seismic design, software, ductility verification, shear walls

Oprite Bobmanuel and Ehab Zalok

Oprite Bobmanuel, MASc Candidate, Department of Civil and Environmental Engineering, Carleton University, 1125 Colonel By Dr, Ottawa, ON K1S 5B6, oprite.bobmanuel@carleton.ca
Ehab Zalok, Professor, Department of Civil and Environmental Engineering, Carleton University, 1125 Colonel By Dr, Ottawa, ON K1S 5B6, ehab.zalok@carleton.ca

ABSTRACT
The effect of fire temperatures on concrete masonry has been an area of interest over the years. The performance of concrete masonry during a fire has been concluded to be excellent because of its non-combustible nature, exceptional thermal properties, and stability. Hollow blocks with vertically oriented cavities are widely used in order to reduce heat flow through a wall. However, heat transfer predominantly by radiation and convection through the cavities is of major concern, as the hot gases in the cavities travels upward and increase the heat flow in the blocks. This gives rise to the need to further improve the fire resistance of concrete masonry blocks through the use of a lightweight insulating materials placed in the cavities. This study involves the use of alternative approach to study the thermal behaviour of normal weight concrete masonry walls with gypsum and polystyrene materials as fillers in the block cells. A finite element thermal analysis was conducted using ABAQUS CAE 14 on hollow concrete masonry blocks. The results obtained were compared with the air-filled masonry walls. All the walls failed due to the 180 oC insulation failure criteria. The walls with gypsum and polystyrene inserts had improved fire resisting properties than those with air-filled cavities. They improved the fire resistance of masonry concrete blocks by an additional 48mins.

KEYWORDS: concrete masonry, fire, gypsum, heat transfer, insulation, modelling

Tarek El-Hashimy, Mohamed Ezzeldin, Wael El-Dakhakhni and Michael Tait

Tarek El-Hashimy, Assistant Professor, Civil Engineering Department, AinShams University, Cairo, Egypt, t.hashimy@eng.asu.edu.eg
Mohamed Ezzeldin, Assistant Professor, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, ezzeldms@mcmaster.ca
Wael El-Dakhakhni, Professor, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, eldak@mcmaster.ca
Michael Tait, Professor, Department of Civil Engineering, McMaster University, Hamilton, ON, L8S 4L7, Canada, taitm@mcmaster.ca

ABSTRACT
Although boundary elements have been demonstrated to enhance the in-plane performance of reinforced concrete block shear walls under seismic loading, research evaluating their effect on the
walls’ out-of-plane performance (e.g., due to earth pressure, wind loading, or blast loading) is very scarce. As such, current blast standards do not assign unique design requirements or response limits for reinforced concrete block walls with boundary elements due to the limited number of relevant studies published when these standards were originally developed. To address this knowledge gap, an experimental program has been conducted to investigate the out-of-plane performance of four scaled seismically-detailed reinforced concrete block axially loaded walls with boundary elements under quasi-static displacement-controlled cyclic loading. The resistance function of the walls and the corresponding damage sequence, as well as the ductility capacity, were also used to assess the walls’ out-of-plane performances. The experimental results in the current study demonstrated the importance of considering the two-way bending mechanism associated with reinforced concrete block walls with boundary elements when their performance is evaluated under out-of-plane loading demands.

KEYWORDS: boundary elements, experimental resistance functions, out-of-plane, reinforced masonry