Masonry Barrel Research Articles

Failure Analysis of Skewed Persian Brick Masonry Barrel Vaults: Experimental and Numerical Study

Failure Analysis of Skewed Persian Brick Masonry Barrel Vaults: Experimental and Numerical Study

Topology Optimization of the FRP for strengthening of masonry barrel vaults

Composite materials are commonly used to preserve historical structures for future generations. The optimum use of composite materials in strengthening masonry buildings and structural elements is a critical issue that needs solutions. This study aimed to determine the effect of optimal reinforcement arrangements on masonry vaults. Numerical models were created using a 3D macro modelling approach and validated with experimental and numerical data from the literature. The study compared the effectiveness of three strengthening procedures using carbon or glass fibre-reinforced fabric materials on masonry vaults under different loads, aiming to determine the most effective procedure, material type, and amount. Results showed that the intrados strengthening procedure was more effective than the extrados, and carbon fibre-reinforced fabric material was generally more effective than glass fibre-reinforced fabric material. The research demonstrates that using significantly less material can still achieve high efficacy. Additionally, the article presents various suggestions for practical situations.

Vulnerability of Pointed Masonry Barrel Vaults Subjected to Differential Settlement Simulated with a GPGPU-Parallelized FDEM

Pointed masonry barrel vaults are widely used in classical historic structures, such as cathedrals and aqueducts, and they are very sensitive to differential settlement. These vaults are assemblages of masonry units and mortar. Since the bonding strength of mortar degrades over ages, dry-joint assumption is widely accepted. Failure behavior of dry-joint pointed masonry barrel vaults subjected to differential settlement is highly complex, discontinuous, and nonlinear. In this study, a 3D GPGPU-parallelized hybrid finite-discrete element method (FDEM), which is an advanced extension of finite element method (FEM) and discrete element method (DEM), is employed to investigate the capacity of pointed masonry barrel vaults subjected to differential settlement. When modeling barrel vaults with 3D FDEM, each masonry unit is discretized into a couple of four-node tetrahedral elements whose deformability is characterized by standard finite element formulation. Thus, structural deformation and interaction forces can be obtained in an accurate manner. Numerical examples are presented and validated with results from literatures. A base case is selected, and the influence of embrace angle ([Formula: see text], sharpness (Sh), stockiness (St), and out-of-plane length ([Formula: see text] on the failure behavior is parametrically investigated. The larger the [Formula: see text] or Sh, the smaller the ultimate settlement. The same applies to St in general, while an excessively large St results in small ultimate settlement due to sliding. The influence of [Formula: see text] can be mitigated should it is large enough compared with the span. It is demonstrated that the 3D GPGPU-parallelized FDEM is a robust tool for analyzing the vulnerability of pointed masonry barrel vaults subjected to differential settlement.

Settlement of masonry barrel vaults: an experimental and numerical study

The paper deals with a experimental and numerical study of a masonry barrel vault subjected to an incremental horizontal settlement of one abutment. The analyzed vault is very slender and with no backfill, as is typical of the vaulted roofs covering many Italian churches and other religious buildings of various dimensions, that often suffer a certain amount of settlement due to the deformation of the sustaining walls. In this paper, the experimental tests conducted at the University of Florence on a full-scale specimen has been assumed as a benchmark for numerical simulations carried out via different models, some implemented in the general purpose FEM software (Abaqus), and others specifically developed for masonry structures (Mady). The capability of the considered models to describe the actual behavior of the vault has been investigated, and their potential highlighted.

Seismic in-plane displacement capacity of masonry barrel vaults: the role of constructive aspects

Historic masonry vaults are one of the most vulnerable elements with respect to the seismic action. Cracks are often detected after post-earthquake surveys. However, it is difficult to directly link the observed damage to causes. Different mechanisms can occur during an earthquake, such as in-plane horizontal shear distortion or longitudinal opening/closing of the abutments. These mechanisms are not necessarily associated to a specific crack pattern, since other factors are involved in the determination of the detected crack status. Among these factors, constructive aspects (such as the brick pattern) play a major role. This study aims at investigating the possible correlation between constructive aspects and the crack pattern in barrel vaults subjected to in-plane shear mechanism. Numerical simulations are carried out on an ideal circular vault with a rectangular base of dimensions 3.1 × 5.3 m, and rise of 1.175 m. Three brick patterns are considered: radial, diagonal and vertical. In order to investigate these aspects, a micro-modelling numerical approach has been adopted. Results are presented in terms of ultimate displacement capacity, collapse mechanisms and crack pattern charts.

Effect of hemp bio composite strengthening on masonry barrel vaults damage

Masonry vaults are common structural elements of the Italian architectural heritage, significantly vulnerable to seismic loads. For this reason strengthening is often required. In the last decade, the use of traditional reinforcement techniques has been progressively replaced by Fiber Reinforced Polymers (FRP) bonded at the vault extrados/intrados. However, this approach has shown drawbacks mainly associated to the polymeric nature of matrix and physical compatibility between the matrix and the masonry support. Consequently, FRP strengthening evolved to innovative composite materials obtained by cement based matrix, i.e. Fiber Reinforced Cementitious Matrix (FRCM). Moreover, within the growing environmental sustainability issues, the scientific research is focusing on the development of biodegradable composite materials, based on vegetal fibers and natural matrices. This paper presents the results of experimental tests on two full-scale masonry vaults with the same geometry and mechanical properties: one is unreinforced and one is reinforced at the extrados by continuous bidirectional hemp ropes bonded in a layer of cocciopesto matrix (i.e. a mix of ground clay bricks and organic binder). The two models were built and tested in the 3D shaking table system of the Laboratory of Earthquake Engineering and Dynamic Analysis (LEDA) at Enna Kore University. Each vault was subjected to seismic loads and dynamic identification tests: the seismic load was given with increasing amplitude at the base of the two models while the dynamic identification tests were carried out after each seismic sequence in order to evaluate the variation of the dynamic properties, testifying structural damage. The strengthening effectiveness was assessed by comparing the damages detected on the unreinforced and reinforced masonry vaults. Results showed that the proposed bio composite strengthening material is effective for improving the seismic performance of masonry vaults.

An effective numerical modelling strategy for FRCM strengthened curved masonry structures

Fabric Reinforced Cementitious Matrix (FRCM) composites are currently considered a very effective solution for strengthening masonry constructions. However, the mechanical interactions governing the response and the strength of FRCM reinforced masonry structures are very complex, especially in the case of curved structures. Moreover, these interactions involve several interfaces between different materials. Thus, the development of accurate numerical models for curved FRCM reinforced masonry structures comes up against several difficulties, and models too complex for practical applications can be obtained. In addition, several mechanical parameters needed for the calculations are generally inaccessible by conventional experimental tests.Here, a suitable numerical modelling strategy for FRCM strengthened curved masonry structures is proposed to combine the accuracy in simulating the actual behaviour in terms of stiffness, strength and collapse mechanisms with a reasonable simplicity, making the proposed approach usable also by practitioners, by adopting commercial codes and at a moderate computational effort. The relatively small number of mechanical parameters characterizing the model can be determined by ordinary experimental tests on materials or by literature formulations.The proposed modelling strategy is validated with respect to experimental data found in literature concerning a FRCM reinforced masonry barrel vault, and then is employed for studying the seismic capacity of the vault through a pushover analysis. A broad sensitivity analysis sheds light on the effect of variations of the mechanical parameters on the predicted overall behaviour, showing the robustness of the results obtainable through the proposed approach concerning inaccuracies in the determination of the parameters often very difficult to determine by ordinary experimental tests on masonry structures.

Effect of brick arrangement on structural behaviour of Persian brick masonry barrel vaults by micro-modelling

In this paper, the effect of brick arrangement on structural behaviour of Persian brick masonry barrel vaults has been studied by the micro-modelling method using non-linear finite element analysis performed by the ANSYS code. Vaults have semi-circular, pointed and four-centred cross-sectional shapes. Two different spans and three different lengths, with Roman brick arrangement and Persian brick arrangement have been considered. The vaults have been subjected to linear load at mid-span, linear load at one-third-span, support settlement, inward rotation of one support, inward rotation of two supports and outward rotation of two supports. In the cases of linear load at mid-span and support settlement, the Persian brick arrangement is more satisfactory in the semi-circular and pointed vaults, and the Roman brick arrangement is favoured in the four-centred vault. In the case of linear load applied at one-third-span, the load-bearing capacity provided by the Persian brick arrangement is up to two times the Roman brick arrangement. When one support rotates inwards, the Roman brick arrangement is always better. For both cases of inward and outward rotation of two supports, the performance of the Persian brick arrangement is more satisfactory in pointed and four-centred vaults, and that of Roman brick arrangement is better in the semi-circular vault.

DEM analysis of the effect of bond pattern on the load bearing capacity of barrel vaults under vertical loads

Bond patterns influence responses of masonry barrel vaults to mechanical loads. In this research, the discrete element method (DEM) was applied to investigate how bond patterns affect the static load bearing capacity of barrel vaults under vertical loads. The two most widely-used bond patterns (transverse and longitudinal) were studied. Using a commercial DEM software, 3DEC, vaults with different angles of embrace were prepared according to both patterns, and then loaded in three alternative ways until failure. The failure loads were recorded, and compared for the two alternative patterns of each overall geometry. Two competing effects were found: 1) in transversal vaults the arches work nearly independently of each other which decreases the load resistance in comparison to longitudinal vaults; 2) larger size of the voussoirs along the arch direction increases the load bearing.

DEM analysis of the effect of bond pattern on the load bearing capacity of barrel vaults under vertical loads

Bond patterns influence responses of masonry barrel vaults to mechanical loads. In this research, the discrete element method (DEM) was applied to investigate how bond patterns affect the static load bearing capacity of barrel vaults under vertical loads. The two most widely-used bond patterns (transverse and longitudinal) were studied. Using a commercial DEM software, 3DEC, vaults with different angles of embrace were prepared according to both patterns, and then loaded in three alternative ways until failure. The failure loads were recorded, and compared for the two alternative patterns of each overall geometry. Two competing effects were found: 1) in transversal vaults the arches work nearly independently of each other which decreases the load resistance in comparison to longitudinal vaults; 2) larger size of the voussoirs along the arch direction increases the load bearing.

Cyclic behavior of masonry barrel vaults strengthened through Composite Reinforced Mortar, considering the role of the connection with the abutments

The original results of experimental investigations concerning the reduction of the seismic vulnerability of masonry vaults through Composite Reinforced Mortar (CRM) are presented in the paper. The transversal performances of full scale, masonry barrel vault samples (i.e. running bond pattern vaults and brick in folio vaults) carrying their own weight and reinforced at the extrados or at the intrados are investigated through cyclic tests. The connection of the reinforced vaults with the masonry abutment is particularly considered and discussed, due to the importance of this detail to avoid uplift and slip at the skewback sections and better exploit the CRM benefits. The experimental behavior of the vault samples is described and analyzed in terms of global behavior, crack pattern and load–displacement curves, also in comparison with the unreinforced configurations. The CRM allowed significant improvements in both vaults strength and displacement capacities, as contrasted the cracks opening and foster the spreading of cracks all along the vault. Considerable performances emerged also in terms of dissipative capacities, with a mean damping value of about 13% in the post-cracking configuration. The vault-to-wall connection, based on embedded steel and composite bars, resulted essential for avoiding dangerous vault sliding at skewback sections, that may reduce the vault performances and also cause the fall from the support.

Parametric study of the effect of hollow spandrel (Konu) on structural behaviour of Persian brick masonry barrel vaults

In this paper, the structural analysis of Persian brick masonry barrel vaults with hollow spandrels (konu) with seven different arches of semi-circular, drop, ordinary and raised pointed, and drop, ordinary and raised four-centred under uniformly distributed load, linear load, pier settlement, pier rotation, temperature and the earthquake has been performed. Non-linear behaviour has been assumed for the materials. The finite element code ANSYS has been used for analysis. The Willam-Warnke failure criterion has been used for brick masonry. The case of equal heights of konus and vaults of the structure has been the most favourable case. The settlement of the middle pier has been the most inappropriate case and the structure has failed quickly. For different cases of pier rotation, the pointed arch has had a better performance than the semi-circular and four-centred arches. For the temperature, the induced displacement in the pointed arch has been more than other arches. Under different states of earthquake analysis, all structures have been failed. Konus are the starting points of cracking and they always contribute to the failure mechanism.

Historic Barrel Vaults Undergoing Differential Settlements

ABSTRACT A principal reason of damage in historic masonry vaults consists in relative displacements of the vaults’ abutments. Excluding the case of seismic-induced damage, cracks are often produced by differential settlements generated by the lateral wall instability or soil degradation (e.g., due to stress concentrations, non-uniform soil stratigraphy, flooding phenomena etc.). When dealing with historic vaults, the effects of long-term deformation processes cannot often be linked directly to causes, which may also be unknown. In this article, the effects of differential settlements on historic masonry barrel vaults are investigated. An efficient 3D contact-based model was developed to reproduce experiments on a scaled pointed barrel vault (representative of a typology of late-medieval barrel vaults in Scotland) under non-uniform differential settlement. First, the numerical model is used to simulate the experimental campaign, achieving good agreement in terms of crack pattern (longitudinal shear) and transverse-longitudinal deformation profiles. Then, further analyses are carried out to gain insight on the effects of several plausible uniform and non-uniform settlement patterns on representative historic barrel vaults. Various settlement configurations were analysed and complex failure patterns observed. This study could help analysts in understanding the nature of on-going deformation process in historic masonry vaults and engineers in the design of strengthening strategies.

Ductility-based incremental analysis of curved masonry structures

Abstract In many engineering applications the limit analysis theorems can be used to estimate the ultimate capacity of several structures. However, the limit analysis can be applied on structures with an adequate plastic capacity. When the goal is to evaluate the ultimate capacity of masonry structures, they could show some drawbacks. For this reason, the incremental analysis represents a valid alternative to estimate the ultimate capacity of masonry structures. These structures could show brittle failures before the hinge mechanism. It is a key aspect especially for curved masonry elements like as arches and vaults. The work focuses on the incremental analysis of masonry barrel vaults without backfill. An analytical model in the framework of the incremental analysis has been proposed. The analytical model allows to assess both the ultimate capacity and the ductility of the masonry barrel vaults. In the first part, the proposed model has been discussed. Then, parametric analysis was performed to assess the impact of physical, geometrical and mechanical parameters on the ultimate behaviour. The numerical results allow to identify some structural examples where the brittle behaviour becomes crucial. Finally, the proposed model was validated with experimental results on a full-scale masonry barrel vault.

Experimental behaviour of non-structural masonry vaults reinforced through fibre-reinforced mortar coating and subjected to cyclic horizontal loads

The paper collects the results of an innovative experimental campaign carried out on full-scale, non-structural masonry barrel vaults, so to assess, by means of quasi-static cyclic tests, the lateral performances of a strengthening technique based on the application, at the extrados or the intrados, of a 30 mm thick mortar layer with Glass Fiber-Reinforced Polymer meshes embedded. The samples were made of solid bricks, with a radius of 2060 mm and are 770 mm wide and 120 mm thick; three vaults have a span of 3980 mm and other three of 3575 mm. It emerged that the presence of the composite mesh contrasted the collapse mechanism, leading to resistance increases ranging from 2 to 4 times that of plain masonry and increasing considerably the ultimate horizontal displacements at crown section. A simplified analytical approach is also presented in the paper, to quantify the samples lateral resistance for assigned geometry and mechanical characteristics of materials.

Numerical Modelling of Masonry Barrel Vaults Reinforced with Textile Reinforced Mortars

Among masonry buildings characterized by a complex architecture, a significant portion is represented by heritage buildings. A significant seismic vulnerability is due to the presence of thrusting elements like as arches and vaults. Their ultimate capacity can be improved by means of several strengthening techniques. However the advantages of using Textile Reinforced Mortars (TRM) are well highlighted in the scientific literature.The present work focuses on ultimate behaviour of masonry barrel vaults, in the framework of incremental analysis, including the strengthening effect. The analytical model is compared in terms of ultimate capacity and failure mode with a full scale masonry barrel vault dynamically tested. After the first tests, the vault has been strengthened with Textile Reinforced Mortar (TRM) and tested again.

Experimental Behavior of Masonry Vaults Strengthened with Thin Extradoxal or Intradoxal Layer of Fiber Reinforced Lime Mortar

The results of a first experimental research program on masonry vaults strengthened by means of GFRP meshes embedded in a thin layer of lime mortar, are herein presented. The tests were designed to reproduce the pattern of a transversal horizontal load proportional to the vault self-weight. The typical simplified loading patterns generally used for the experimental tests concern concentrated vertical loads at the crown section or at 1/4 of the span, but some numerical investigations evidenced that these configurations are not able to reproduce the actual behavior and the effectiveness of the reinforcement. So a specific rig was designed to apply the horizontal load pattern.Solid brick masonry barrel vaults were considered (thickness 120 mm, arch span 4000 mm, arch rise/radius = 0.75). Three quasi-static cyclic tests were performed: the first concerned an unreinforced vault, the second a vault reinforced at the extrados through the application of a mortar coating reinforced with a GFRP mesh and the third reinforced at the intrados surface with the same technique. The experimental results demonstrated the technique effectiveness and the important increment of ductility of the vaults.

Discrete element analysis of gothic masonry vaults for self-weight and horizontal support displacement

The paper investigates how the deviation of the centreline from the semi-circle influences the mechanical behaviour of gothic masonry vaults. The geometry of the vaults is quantified by a scalar parameter. The present work deals with the force-transmitting system, crack opening magnitude and pattern. Furthermore, the magnitude of the so-called threshold support displacement and the magnitude of the support displacement at first failure is also analysed. Masonry structures consist of separate blocks, each of which can move independently from each other, which makes the calculation process rather complicated. The Discrete Element Method (henceforth DEM) is used to solve the highly nonlinear problem. In the chosen method the equations of motion are solved by the central difference scheme. Approximate boundary conditions are applied, which assume symmetry in the analysed structures. The main findings of the work are: barrel vaults with pointed shape become statically determinate at a higher support displacement level than barrel vaults with semi-circular centreline. In the case of large deviation from the semi-circle or at large support displacement level shear failures can appear in gothic masonry barrel and cross vaults, which could decrease the magnitude of feasible horizontal support displacement.

Seismic retrofitting of masonry vault using CFRP

Masonry vaults represent one of the most seismic vulnerable element in an ancient building. It also generally does not possess an adequate capability of redistribution of the seismic action among the walls of the buildings. In this paper, the structural behaviour of a masonry barrel vault strengthened by a new technology in applying Carbon Fiber Reinforced Polymer (C-FRP) is discussed from both theoretical and experimental point of view. The C-FRP is applied such as to assume an Ω shape around a concrete core realized at the vault extrados. This arrangement allows the resulting CFRP reinforced ribbed vault to assume the necessary strength and membranal and flexural rigidity so as to ensure the aforementioned seismic action redistribution capability and to avoid local collapse of the vault. A theoretical prediction of ultimate strength was derived in agreement with the occurrences observed during the experiments (masonry crushing, FRP rupture, debonding, sliding along the mortar joint). To this aim, a novel incremental step-by-step lower bound limit analysis approach was developed taking into account for the shear failure mechanism at each mortar joint. The shear strength is evaluated by the Mohr-Coulomb friction law for the mortar joint and by other nonlinear Italian Code relations for CFRP Ω-Wrap reinforcement. In the approximated incremental analysis process the current value of the shear strength, depend on the compressive stress resulting from the previous step.

The Effect of Boundary Conditions on the Behaviour of Pointed Masonry Barrel Vaults: Late Gothic Cases in Scotland

Barrel vaults provide effective fire-proof roofing in historic churches, castles, cloisters or halls that look for simple and utilitarian aesthetics, as long as they are strongly connected to sturdy lateral walls and transverse gables, conditions that limit their possibilities for spatial expression. A study of the effect of these conditions was carried out on the pointed vaults of a characteristic group of 15th century Scottish churches. Following earlier measured surveys that showed remarkable geometric integrity, 1/15-scale models of a representative form were made in reinforced plaster that could delay the cracks propagation enough to be monitored. Only the shell was considered, leaving the effect of ribs or diaphragms that hold the heavy flagstone roof for further study. The model was subject to symmetric and asymmetric horizontal spread, which simulated the insufficient containment of not very stiff walls, but included the effect of gable end walls. Cracks formed invariably at an early stage (3% of the span spread), propagating more rapidly and causing early failure at a symmetrical spread (15% of span), while the asymmetrical spread produced diagonal crack patterns across the vault at 33% of the span. Gables provided more stiff areas but eventually caused local detachment at the spread point, at only 5% of the span, with cracks propagating to the back wall and at a higher rate when a less stiff gable was included(13% of span). The results validated an FE model that provided further insight to the performance of the type at displacement and settlement, as exemplified in the case of Bothwell church in Scotland.