Capacity interaction in brick masonry under simultaneous in-plane and out-of-plane loads

A considerable number of numerical and experimental studies, carried out to-date to investigate the behaviour of masonry walls under seismic loading, have considered the in-plane or the out-of-plane response of the wall separately without due consideration for any possible interaction between the two responses. In this paper, the results of a series of tests with different levels of simultaneous in-plane shear and out-of-plane bending actions on small brick walls are presented. The tests results indicate noticeable interaction between the in-plane shear and out-of-plane bending strengths of brick walls. Test results are also used to validate representing numerical models of wall panels. The combined in-plane/out-of-plane capacity interaction in full-scale walls having different aspect ratios is then investigated using these numerical models. It is found that the wall aspect ratio highly influences the interaction level, which must be considered in masonry design

Evaluation of timber floor in-plane retrofitting interventions on the seismic response of masonry structures by DEM analysis: a case study

The seismic response of existing masonry structures is strongly influenced by floor and roof in-plane properties. A strengthening intervention is often needed for traditional timber floors to overcome their low in-plane stiffness and to preserve historical buildings. In this study, the effects of unreinforced and reinforced timber floors on the seismic behaviour of an existing listed masonry building are investigated with dynamic non-linear analyses by means of the Discrete Element Method (DEM). With this approach, the failure processes and collapse sequences of masonry structures can be captured in detail. A previously developed model of the floor cyclic behaviour, based on experimental data, is applied herein to DEM models of the masonry building. Different seismic ground accelerations, different floor types and different floor-to-wall connections are considered. The results highlight the effectiveness of the analysed floor strengthening solution in reducing the out-of-plane displacements of masonry walls. With adequate connections, the reinforced floor is able to transfer the seismic forces to the shear-resistant walls up to the shear-sliding collapse of the structural sidewalls. A comparison with the ideal rigid diaphragm case confirms the good performance of the strengthened floors. The small observed out-of-plane displacements are compatible with the masonry wall capacity, and the reinforced floor hysteretic cycles contribute to dissipate part of the input energy. Moreover, different designs of the connections can also cap the transferred seismic forces to an acceptable level for shear-resistant walls

Unifying Assessments of Sustainability and Resilience in Civil Infrastructure Systems: The Case of Masonry Structures

Review of existing literature on the unification of sustainability and resilience showed the lack of a single effective framework that can unify the two, especially for building systems. Along this line of research, this study contributes a novel experimental framework to assess masonry structures and support a unified approach. This study performed structural analysis for resilience assessment and energy simulation for sustainability assessment. Based on the openings available in masonry walls, the study observed the changes in sustainability indicators (electricity consumption). Changes in resilience indicators (story drifts) were also observed. Results indicate that overall sustainability is compromised with additional openings in most cases. However, in most cases, electricity consumption for space heating decreases with additional openings. Results from resilience assessment show an increase in story drift of different floors with additional openings. Such results indicate that with additional openings, an unreinforced masonry building becomes more vulnerable to the damages from the earthquake lateral loads. Moreover, differential effects (positive/negative correlations) were observed when concurrent assessments were made on sustainability and resilience indicators

Efficacy Assessment of Timber Based In-Plane Strengthening of Wooden Floors on the Seismic Response of Masonry Structures by means of DEM Analyses

Masonry buildings are highly vulnerable to seismic loading, and their dynamic response is strongly influenced by the timber floor in-plane deformability and by the quality of the wall-to-floor connections. Understanding the behavior of timber floors and roofs and their interaction with the masonry walls is therefore important for the protection of historical buildings. In a previous research project, different timber-based dry-connected floor strengthening solutions were tested under in-plane loads. The experimental results show a significant increase in shear strength and stiffness. Discrete Element Method is here used to evaluate the effectiveness of the strengthening solutions in avoiding the triggering of the out-of-plane collapse of masonry walls, first on a simple masonry cell, and then on a heritage listed masonry building. A detailed cyclic model of the floor behavior was implemented: the unreinforced and reinforced floors were described by beams connected with nonlinear springs, reproducing the experimental hysteretic response. Both the case studies highlight the effectiveness of the strengthening solutions in reducing the out-of-plane displacements of masonry walls, confirmed also by a comparison with the ideal rigid diaphragm case. The reinforced floor is able to transfer the seismic forces to the shear-resistant walls. The out-of-plane displacements are compatible with the wall capacity, and the reinforced floor hysteretic cycles contribute to dissipate part of the input energy. Moreover, a proper connection design can also cap the transferred seismic forces to an acceptable level for shear-resistant walls

A thrust network approach to the equilibrium problem of unreinforced masonry vaults via polyhedral stress functions

The equilibrium problem of unreinforced masonry vaults is analyzed via a constrained thrust network approach. The masonry structure is modeled as no-tension membrane (thrust surface) carrying a discrete network of compressive singular stresses, through a non-conforming variational approximation of the continuous problem. The geometry of the thrust surface and the associated stress field are determined by means of a predictor–corrector procedure based on polyhedral approximations of the thrust surface and membrane stress potential. The proposed procedure estimates the regions exposed to fracture damage according to the no-tension model of the masonry. Some numerical results on the thrust network and crack pattern of representative vault schemes are given

Performance Based Design and Machine Learning in Structural Fire Engineering: A Case for Masonry

The volatile and extreme nature of fire makes structural fire engineering unique in that the load actions dictating design are intense but not geographically or seasonally bound. Simply, fire can break out anywhere, at any time, and for any number of reasons. Despite the apparent need, fire design of structures still relies on expensive fire tests, complex finite element simulations, and outdated procedures with little room for innovation. This thesis will make a case for adopting the principles of performance-based design and machine learning in structural fire engineering to simplify the process and promote the consideration of fire in all structural engineering applications. This thesis begins with an overview of relevant topics, providing context and a frame of reference for the coming chapters. The first section of this thesis argues for the adoption of performance-based design for the structural fire design of buildings, as obtained through a comprehensive and much needed literature review. The second half of this thesis revolves around the application of performance-based design and simple machine learning in our field. An Excel file accompanies this thesis as an easy-to-use tool to encourage the consideration of fire criteria in masonry projects, focusing not on how heat affects the material-level properties but rather on how those effects accumulate to affect the final design requirements. An outline for the development of a coding-free machine learning model capable of predicting failure of unreinforced masonry structural elements exposed to elevated temperatures including its abilities and limitations, is presented. The thesis concludes with a summary of the above information and the potential for related project scopes in the future

THE EVOLUTION OF THE DESIGN AND CONSTRUCTION OF MASONRY BUILDINGS IN CANADA

This paper provides an opportunity to formulate a statement of the current status of masonry engineering in Canada with some perspective from the past and some insight into potential for the future. Notwithstanding the fact that this represents the view of the author only, an attempt is made to provide a balanced and comprehensive overview. When we talk about masonry in Canada, by far the largest part of clay brick production and most of the concrete block used are employed in buildings based on the very simple to apply provisions of Part 9 of the National Building Code that applies to small buildings and is not “engineered” through any proper analysis and does not require the participation of a licensed structural engineer. However, growth potential is greatest in the area of engineered masonry. This paper provides information on education, research, development of codes and standards, and the general state of masonry engineering in Canada. Problems facing masonry in terms of maintaining or expanding market share of construction, areas requiring most attention, and opportunities for enhancement of masonry are discussed

Masonry infill walls under blast loading using confined underwater blast wave generators (WBWG)

The vulnerability of the masonry envelop under blast loading is considered critical due to the risk of loss of lives. The dynamic behaviour of masonry infill walls subjected to dynamic out-of-plane loading was experimentally investigated in this work. Using confined underwater blast wave generators (WBWG), applying the extremely high rate conversion of the explosive detonation energy into the kinetic energy of a thick water confinement, allowed a surface area distribution avoiding also the generation of high velocity fragments and reducing atmospheric sound wave. In the present study water plastic containers, having in its centre a detonator inside a cylindrical explosive charge, were used. Studies were performed in both unreinforced and reinforced walls with 1.7 by 3.5 meters. Bed joint reinforcement and grid reinforcement were used to strengthen the infill walls. Besides the usage of pressure and displacement transducers, pictures with high-speed video cameras were recorded to enable processing of the deflections and identification of failure modes. Two different strengthening solutions were studied under blast loading and the results are presented and compared

Blast loading of masonry infills: testing and simulation

This work intends to present a newly developed test setup for dynamic out-of-plane loading using underWater Blast Wave Generators (WBWG) as loading source. Underwater blasting operations have been, during the last decades, subject of research and development of maritime blasting operations (including torpedo studies), aquarium tests for the measurement of blasting energy of industrial explosives and confined underwater blast wave generators. WBWG allow a wide range for the produced blast impulse and surface area distribution. It also avoids the generation of high velocity fragments and reduces atmospheric sound wave. A first objective of this work is to study the behavior of masonry infill walls subjected to blast loading. Three different masonry walls are to be studied, namely unreinforced masonry infill walls and two different reinforcement solutions. These solutions have been studied previously for seismic action mitigation. Subsequently, the walls will be simulated using an explicit finite element code for validation and parametric studies. Finally, a tool to help designers to make informed decisions on the use of infills under blast loading will be presented