•Effective URM wall-to-horizontal diaphragm connections prevent seismic mechanisms.•Experimentally calibrated connection models should be developed and used.•Steel anchors enhance the PO and shear ...behavior effectively.•Global FEM or EF seismic analyses usually neglect nonlinear connection behavior.•Nonlinear kinematic and rocking models are useful for the local seismic assessment.
Wall-to-horizontal diaphragm connections play a crucial role in the global stability of historical buildings under seismic actions. When these links are ineffective or absent, engineered measures should be considered to enhance the earthquake-resistant box-type behavior. Besides the great variety on the construction systems and materials, common damages were observed in recent seismic events showing the high vulnerability of local mechanisms promoted by the lack of structural integrity. Although the acknowledged importance of connections, this topic has been practically neglected over time among the research community and practitioners and only few of them focused on the influence of diaphragm-to-wall connections on the dynamic behavior of the building as a whole.
This paper presents a literature review of the traditional wall-to-floor or wall-to-roof connections in unreinforced masonry buildings and summarizes typical and innovative strengthening solutions, taking into account the indications provided by the few design codes addressing this topic. Experimental laboratory researches are investigated, including shaking table tests on global and local scale, and cyclic or monotonic tests to characterize anchoring systems. An overview of the typical vulnerability assessment approaches and modelling techniques is given, considering present standards that account for connections.
This paper presents a multi-level experimental and analytical investigation on the mechanical performance of TRM composites used for strengthening existing masonry structures. Micro (fabric-to-mortar ...bond), meso (TRM-to-substrate bond), and macro (TRM tensile response and in-plane and the out-of-plane ressponse of TRM-strengthened masonry) response of TRMs are combined and investigated in-depth for this reason. These results help to understand the mechanisms controlling the response of these composites and their performance at the structural scale.
The use of Textile Reinforced Mortar (TRM) composites for Externally Bonded Reinforcement (EBR) of reinforced concrete (RC) and masonry structures has attracted several attentions during the last ...years. The effectiveness of these composites in structural reinforcement is significantly dependent on the TRM-to-substrate and the fiber-to-mortar bond behavior. Despite the importance of the latter, that controls the crack distribution on these composites, have received few attentions and is relatively unknown.
This paper presents a combined experimental and analytical study on the effect of fiber-embedded length and configuration on the pull-out response. From the obtained results, bond-slip laws are proposed for TRM composites made of unidirectional and bidirectional grids. The tests are performed on a (unidirectional) steel-based and a (bidirectional) glass-based TRM composite as common reinforcing systems. A comparison is also made between the results obtained from single-fiber pull-out tests and conventional single-lap shear bond tests to highlight the differences/similarities between these two test methods.
The corner mechanism in masonry structures is one of the out-of-plane modes that may frequently occur under dynamic actions such as earthquakes. The three dimensional motion, in principle complex to ...treat, can be simplified into a two-dimensional problem, where a prismatic equivalent block is associated to the corner mechanism. This paper provides a method to treat the corner mechanism in two dimensional rocking analysis, taking into account the roof actions – especially the roof thrust that acts as destabilizing force in the preliminary phases of motion – and the boundary conditions such as the transverse walls. A case study is taken as benchmark to perform rocking non-linear analyses and discuss the role of geometry, energy dissipation and boundary conditions. It is shown the relevant influence of the geometry and of the coefficient of restitution on the stability conditions, whenever the oscillation produce horizontal displacement values of some cm. The results of the case study, subjected to the Central Italy earthquake, are compared to the actual response of the corner mechanism, which collapsed during this seismic swarm, showing that the rocking analysis on the equivalent block correctly predicts the collapse occurred.
•A methodology to treat the dynamic problem of the masonry corner mechanism is provided.•The influence of geometry is extensively discussed through numerical examples.•The role of energy dissipation and boundary conditions (adjacent walls) is analyzed.
•Masonry panels reinforced with NSM bars and FRCM composites are diagonally loaded.•Symmetric and asymmetric strengthening configurations are considered.•Mechanical parameters are discussed ...introducing a calibrated reinforcement ratio.•Analytical procedures are followed to predict the shear capacity of the panels.
Results of an experimental campaign conducted on plain and reinforced masonry wallettes subjected to diagonal compression tests are presented in this paper. The masonry panels were reinforced by means of two strengthening techniques: structural repointing achieved by inserting basalt bars in the mortar bed joints and fiber reinforced cementitious matrix (FRCM) composite, obtained by applying a single-ply glass mesh on the sides of the specimens. The structural effects of symmetric and asymmetric strengthening configurations are investigated. The main mechanical parameters, such as shear capacity, ductility and shear modulus, are compared and discussed introducing a calibrated reinforcement ratio. Further, analytical procedures presented in the codes and in literature are followed to predict the shear capacity of the unstrengthened and strengthened wallettes and, finally, compared to the values obtained experimentally.
•Steel reinforced grout is used for strengthening bricks and bond behavior is investigated experimentally and numerically.•Between mortar curing time and brick surface preparation, the latter ...influences remarkably the bond performance.•The numerical model of the experiments is introduced comprising of bond–slip laws obtained through inverse fitting procedure.•The effect of some design parameters on the overall bond behavior is studied using the validated numerical model.
Innovative materials such as steel reinforced grout (SRG) have shown superior behavior in terms of sustainability and compatibility comparing to their FRP counterparts for external strengthening of masonry structures. Considering the critical bond mechanisms at interfaces, this paper addresses an experimental and numerical investigation on bond in SRG-strengthened masonry by performing conventional single-lap shear bond tests revealing the importance of substrate preparation for application of SRG followed by a numerical model proposing suitable interfacial bond-slip laws. The numerical model, once validated against experimental results, is used to investigate further aspects of the bond behavior and the results are discussed.
The present paper describes the seismic assessment of the Qutb Minar in Delhi, India. Three models with different levels of complexity and simplification were developed. The use of these models ...allows one to overcome the complexity of the study of the seismic behavior of ancient masonry structures; by combining the results of the different models it is possible to obtain a better and more comprehensive interpretation of the seismic behavior. The models were used for non-linear static (pushover) and non-linear dynamic analyses. The static and dynamic analyses give different behaviors, indicating that the push-over analysis should be used carefully in the seismic assessment of masonry structures. For the static analysis, the base of the tower is the most vulnerable part; while according to the dynamic analysis, it is the upper part of the tower. This last behavior is according to the historical damage suffered by the tower due to earthquakes. The different behaviors can be explained by the influence of the higher modes of vibration.
Textile-reinforced mortars (TRM) have recently received significant attention for the externally bonded reinforcement (EBR) of masonry and reinforced concrete structures. The fiber-to-mortar bond, ...the TRM-to-substrate bond, and the mechanical properties of the TRM constituents have a fundamental role in the performance of this strengthening technique and therefore require special attention. Despite this importance, only few investigations are devoted to characterization of the single fiber-to-mortar bond response in these systems.
This paper, as an step towards addressing the fiber-to-mortar bond, presents a combined experimental and analytical investigation on the effect of test setup on the pull-out response and bond-slip laws in TRM composites. Three different pull-out test setups, consisting of one pull-pull and two pull-push configurations, are developed and investigated for characterization of the single fiber-to-mortar bond behavior. The experimental and analytical results are critically discussed and presented and bond-slip laws are extracted for each test setup.
•A comprehensive non-destructive testing campaign of an historical stone arch bridge is presented.•A three-dimensional non-linear finite element modelling strategy for masonry arch bridges is ...adopted.•Finite element model updating is performed through optimization procedures.•The key role that fill materials play in the structural behavior of masonry arch bridges is demonstrated.•The critical importance that transverse effects have on the strength capacity of masonry arch bridges is evidenced.
In this work a multidisciplinary approach for the structural assessment of masonry arch bridges is presented. The Vilanova Bridge, located in Galicia, northwest of Spain, is considered for the implementation of the methodology. A comprehensive field survey fully based on non-destructive testing techniques, which integrates laser scanning, ground penetration radar, sonic tests and ambient vibration testing, is proposed. It provides all the necessary geometric data to build an accurate and detailed three-dimensional finite element model. The calibration of the model is then carried out through the coupling with an optimization algorithm, which minimizes the discrepancies with respect to the experimentally obtained modal properties. The structural analysis of the bridge is addressed in the last stage. A sensitivity analysis involving different loading scenarios and the plausible variation of the masonry and soil material properties is performed. The results demonstrate the significant influence of tensile non-linear properties of masonry, but also the key role played by fill materials on the arch bridge performance. Lastly, the advantages of adopting a three-dimensional modelling approach are also pointed out, since the apparition of critical transverse effects in the response of the structure is successfully captured by the developed numerical model.
Historic masonry buildings are characterised by uniqueness, which is intrinsically present in their building techniques, morphological features, architectural decorations, artworks, etc. From the ...modelling point of view, the degree of detail reached on transforming discrete digital representations of historic buildings, e.g., point clouds, into 3D objects and elements strongly depends on the final purpose of the project. For instance, structural engineers involved in the conservation process of built heritage aim to represent the structural system rigorously, neglecting architectural decorations and other details. Following this principle, the software industry is focusing on the definition of a parametric modelling approach, which allows performing the transition from half-raw survey data (point clouds) to geometrical entities in nearly no time. In this paper, a novel parametric Scan-to-FEM approach suitable for architectural heritage is presented. The proposed strategy uses the Generative Programming paradigm implementing a modelling framework into a visual programming environment. Such an approach starts from the 3D survey of the case-study structure and culminates with the definition of a detailed finite element model that can be exploited to predict future scenarios. This approach is appropriate for architectural heritage characterised by symmetries, repetition of modules and architectural orders, making the Scan-to-FEM transition fast and efficient. A Portuguese monument is adopted as a pilot case to validate the proposed procedure. In order to obtain a proper digital twin of this structure, the generated parametric model is imported into an FE environment and then calibrated via an inverse dynamic problem, using as reference metrics the modal properties identified from field acceleration data recorded before and after a retrofitting intervention. After assessing the effectiveness of the strengthening measures, the digital twin ability of reproducing past and future damage scenarios of the church is validated through nonlinear static analyses.
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