Description
Technical Papers
Author: Richard M. Bennett
Abstract
TMS 402-22 provides an equation for determining the cracked moment of inertia of a reinforced masonry wall under out-of-plane loading. TMS 402-22 states that the equation is valid for a fully grouted wall or a partially grouted wall with the neutral axis in the face shell. Other implicit assumptions that are not stated in TMS 402-22 are that the tension reinforcement has yielded, there is only one layer of tension reinforcement, and the axial load can be replaced by equivalent reinforcement at the mid-depth of the section, with the area of the reinforcement being the factored axial load divided by the yield stress. This paper provides equations for the cracked moment of inertia when these assumptions are not met. Tips for design are also provided.
Keywords: Masonry design, out-of-plane, cracked moment of inertia, reinforced masonry
Authors: Dipayan Jana and Shubham N. Mahajan
Abstract
A large stone barn built in 1820s in the Valley Forge historic national park in Pennsylvania used some of the early historic lime mortars in the US masonry construction during the time when natural cement was just produced in the US and about to gain its momentum for next 70 years, and Portland cement, though formulated in Europe, didn’t enter the US market for at least 50 years. A brown original fist-size bedding mortar fragment was examined, which showed many interesting microstructures of a clay-mixed historic lime mortar. The fragment was examined by a plethora of analytical techniques encompassing optical and scanning electron microscopy and microanalysis, acid digestion, chemical (gravimetric) analysis, XRD, XRF, thermal studies (TGA, DSC, DTG), FTIR, and ion chromatography. Such a comprehensive investigation provided detailed information about the mortar type, composition, and grain size distribution of masonry sand, original non-hydraulic dolomitic lime plus clay-based binder compositions and resultant microstructure of paste, origin of lime lumps, along with evidence of any distress and alterations from two centuries of exposures to a moist outdoor environment. Based on all these studies, the overall condition, extent of deterioration/alterations, and sand and binder proportions of the original mortar were assessed by reverse engineering, from which a suitable replacement mortar was recommended for long-term restoration.
Keywords: Microscopy, petrography, masonry, historic mortar, lime
Authors: Dipayan Jana and Shubham N. Mahajan
Abstract
A large stone barn built in 1820s in the Valley Forge historic national park in Pennsylvania used some of the early historic lime mortars in the US masonry construction during the time when natural cement was just produced in the US and about to gain its momentum for next 70 years, and Portland cement, though formulated in Europe, didn’t enter the US market for at least 50 years. A brown original fist-size bedding mortar fragment was examined, which showed many interesting microstructures of a clay-mixed historic lime mortar. The fragment was examined by a plethora of analytical techniques encompassing optical and scanning electron microscopy and microanalysis, acid digestion, chemical (gravimetric) analysis, XRD, XRF, thermal studies (TGA, DSC, DTG), FTIR, and ion chromatography. Such a comprehensive investigation provided detailed information about the mortar type, composition, and grain size distribution of masonry sand, original non-hydraulic dolomitic lime plus clay-based binder compositions and resultant microstructure of paste, origin of lime lumps, along with evidence of any distress and alterations from two centuries of exposures to a moist outdoor environment. Based on all these studies, the overall condition, extent of deterioration/alterations, and sand and binder proportions of the original mortar were assessed by reverse engineering, from which a suitable replacement mortar was recommended for long-term restoration.
Keywords: Microscopy, petrography, masonry, lime
Canada/US (CANUS) Collaborative Project Papers
A Harmonization of Canadian and American Masonry Structures Design Standards
Funding for this project was provided jointly by the National Concrete Masonry Association Education and Research Foundation, the Canada Masonry Design Centre, the Canadian Concrete Masonry Producers Association, and the Canadian Standards Association.
Comparison of Reinforced Masonry Design: Project Overview and Design Examples
Authors: Ece Erdogmus, Jason Thompson, Bennett Banting, Helene Dutrisac, Philippe Ledent, Kevin Hughes, Bart Flisak
Abstract
This work is the first one of the four companion papers associated with the Canada/US (CANUS) collaborative project: Harmonization of Canadian and American Masonry Structures Design Standards. This paper provides an overview of the key differences in reinforced concrete masonry design provisions between the two countries. The first part of the paper summarizes these differences in a discussion format, while the second part provides two design examples: a two-story mixed-use occupancy building and a multi-story residential building. Two locations are selected for high and low seismicity. While the critique of the building codes is out of the scope of this study, when appropriate, differences regarding the loading considerations from NBCC 2015 and ASCE 7-16 are highlighted. In some cases, the corresponding design checks align closely between the two countries’ design standards, while in other cases there are minor to significant differences. There are also instances where one of the standards is silent on a topic while the other addresses it comprehensively. In general, it is observed that TMS 402-16 allows a larger applicability of masonry design compared to CSA S304-14 due to the compounding effect of lower trust in masonry’s material strength and stricter considerations in design equations.
Keywords: Reinforced masonry design, masonry codes, compressive strength of masonry, TMS 402-16, CSA S304-14
Comparison of Masonry Beam Design and Detailing Provisions
Authors: Ece Erdogmus, Richard Bennett, Jason Thompson, Bennett Banting
Abstract
This work is one of the four companion papers associated with the Canada/US (CANUS) collaborative project: Harmonization of Canadian and American Masonry Structures Design Standards. This particular paper specifically delves into a comparison of the design and detailing provisions for masonry beams in the U.S. and Canada. The scope of the investigation covers the similarities and divergences between the two design standards (CSA S304-14 and TMS 402-16), through first a comparative discussion of the provisions followed by parametric studies that illustrate the differences quantitatively.
Several areas of further investigation are identified as a result of this work, which if addressed, may improve and harmonize the two standards and practices. For instance, the χ factor utilized in CSA S304-14 amplifies the divergence such that most masonry beam designs that have been safely constructed in the U.S. are not possible in Canada. In contrast, TMS 402-16 does not have clear guidance on deflection limits or intermediate reinforcement for regular beams; and a reconsideration for modulus of rupture values may be warranted, as the code- provided values are based on historic wallette tests instead of beams.
Keywords: Masonry beams, flexure, modulus of rupture, strength design, TMS 402, CSA S304
Comparison of Out-of-Plane Reinforced Masonry Wall Design Provisions
Authors: Heather Sustersic, David Stubbs, Russ Peterson, Richard M. Bennett, Clayton Pettit, Bart Flisak, Ece Erdogmus, Jason Thompson, Semsi Coskun, Bennett Banting, Carlos Cruz-Noguez
Abstract
As part of a larger project jointly sponsored by the National Concrete Masonry Association (NCMA) Foundation, Canadian Concrete Masonry Producers Association (CCMPA), Canada Masonry Design Centre (CMDC) and Canadian Standards Association (CSA), a team of engineers and researchers from U.S. and Canada worked together to examine the key differences and similarities between the design provisions for reinforced masonry walls subject to out-of-plane (OOP) and axial loads. The scope was limited to the strength design provisions of TMS 402-16 and the limit state design provisions of CSA S304-14 masonry design standards. Several parametric studies were conducted to quantify the comparisons, as well as to identify possible limitations within each code. These studies explored factors that directly impact the calculation of combined flexural and axial capacity, wall stiffness, second-order moments, and shear capacity of the masonry walls subjected to OOP loading. Parameters considered include the compressive strength of the masonry assembly, wall geometry, as well as the size, strength and spacing of the steel reinforcement. In general, it was found that the Canadian provisions are more conservative than those in the U.S. The paper also provides a list of areas of further research or code revisions that should be considered in the future. It is the team’s goal to propose improvements to both codes as a result of this work.
Keywords: Flexure, Axial Capacity, Out-of-Plane Resistance of Walls, Reinforced Masonry Walls, Strength Design, TMS 402, CSA S304
Comparison of Reinforced Masonry Shear Wall and Seismic Design Provisions
Authors: Ece Erdogmus, Carlos Cruz-Noguez, Phillipe Ledent, Lane Jobe, Kevin Hughes, Bennett Banting, Jason Thompson
As part of a larger project titled, CANUS: Harmonization of Canadian and American Masonry Structures Design Standards Project, in this paper, the design provisions in TMS 402-16 and CSA S304-14 are compared for reinforced concrete masonry shear walls subject to in-plane forces. The scope of the work covers in-plane bending and axial force interactions, shear capacity calculations, and seismic provisions for fully grouted reinforced concrete masonry shear walls. Seven parametric studies and two case studies are utilized to quantify the impact of some of the differences. The parametric studies include exploration of the effects of the wall aspect ratio, compressive strength of masonry, maximum reinforcement limitations and ductility requirements, material or capacity reduction factors, maximum compressive strain, and the artificial moment arm reduction considerations, as well as seismic wall categories and prescriptive seismic detailing requirements. The authors find that in most cases, the Canadian approach is more conservative than the U.S. The main contributor to this discrepancy is a large difference in the typical masonry compressive strength (f’m) values used in Canada and the U.S. By contrast, the maximum reinforcement ratio combined with a lower maximum strain in U.S. design can limit the height of reinforced masonry walls, especially in high seismic areas. The main product of this project is a list of potential future research studies for the resolution of some of the issues highlighted in this paper that can help improve and harmonize both countries’ masonry design provisions.
Keywords: Reinforced masonry shear walls, TMS 402, CSA S304, In-plane behavior of masonry shear walls, Seismic design of shear walls
