Rubble Masonry Research Articles

Stone instance segmentation of rubble masonry based on laser scanning point clouds

Laser scanning allows for objective area-based analysis of water dam structures to enable targeted interventions in case of displacements, requiring comparison of the same areas over different epochs. This comparison improves if identical areas, e.g. stones, from multiple epochs can be automatically derived in advance. We present an instance segmentation algorithm based on a 3D point cloud with reflected intensity information to identify individual stones in rubble masonry dams that can be used within deformation monitoring. The algorithm uses initial k-means classification followed by image-based processing steps, resulting in a segmented 3D point cloud with individual stones. It is evaluated against a manually labeled reference and analyzed on terrestrial laser scanning (TLS) and UAV-based data sets. Correctly identified stones are 89.92% for TLS and 90.82% for UAV data. Additionally, stone centroids and shapes were evaluated without significant deviation. A first outlook on deformation analysis was provided using ICP matching of stones from two simulated epochs.

How outdoor horticultural activities affect elderly adults' thermal, physiological and psychological responses: a field study.

We recruited 162 healthy elderly adults to determine the thermal, physiological, and psychological effects of horticultural activities (flower arranging, transplanting, and rubble masonry) in outdoor open spaces. We linked these to local climate conditions, physiology, and comfort through a questionnaire survey. The results showed that: (1) the neutral physiological equivalent temperature (NPET) before the horticultural activities were 22.18℃ for flower arranging, 23.67℃ for transplanting, and 20.78℃ for rubble masonry, while the NPET decreased to 18.53℃, 20.73℃ and 18.04℃ (respectively) after activities. (2) The heart rate and blood oxygen saturation changed significantly (p < 0.05) only after rubble masonry. (3) The average positive affect (PA) scores increased after flower arranging by 4.83, transplanting by 3.30, and rubble masonry by 4.00. (4) After activities, the thermal sensation vote was mainly influenced by globe temperature (41.36%), air temperature (33.47%), and wind speed (25.17%). Thermal comfort vote could be promoted because of 37.35% of an increasing positive and 21.20% of decreasing negative emotion.

A new non-invasive method for the seismic retrofit of rubble masonry using composite connectors

A new non-invasive method for the seismic retrofit of rubble masonry using composite connectors

The use of OBIA and petrography in the study of stone masonry: The case of La Palma, Sierra Nevada de Santa Marta

AbstractIn this case study, rubble masonry walls from the Sierra Nevada de Santa Marta in Northern Colombia were investigated. We applied a combined object‐based image analysis (OBIA), photogrammetry, and petrography method to characterize and determine the provenance of the materials used in three targeted terraces of the archaeological site of La Palma. In situ data acquisition included detailed photographic records and petrographic descriptions of a selected section of masonry walls, as well as mapping of local geological units. Photographs were processed using OBIA. The data obtained allowed characterization and systematization of the constructive elements, via parameters that include architectural function within the construction (headers, stretchers, and wedges), roundness, and lithotype. This methodology enabled us to identify the source of the lithotypes from local rock outcrops (metagranodiorite and schist) as well as rock boulders and cobbles from the nearby riverbeds. The results suggest that pre‐Hispanic communities had knowledge of the properties of the geological resources available in the region, which they used to build masonry that has endured more than five centuries. Vertical differences identified in segments of different terrace walls suggest changes in the constructive process and therefore may serve to determine a construction chronology.

Structural Assessment of a Water Reservoir Masonry Vaulted Roof from the Nineteenth Century

This article presents an experimental and numerical study on the structural safety of an old buried water reservoir built in the second half of the nineteenth century. The main goal of the study was to assess the feasibility of changing the reservoir roof from a garden with limited access to an outdoor exhibition or concert area, with an increase in service loads. The reservoir comprises a set of cylindrical vaults, built with rubble masonry and lime mortar, supported by a set of stone masonry arches and columns. Because no original design elements exist, the following methodology was followed: (1) a structural survey was first carried out for geometrical and material identification and for assessment of anomalies; (2) core samples were extracted from the vaulted roof to characterize the material properties of the rubble masonry and lime mortar; (3) a three-dimensional (3D) nonlinear finite element (FE) model of the structure was developed and used for structural safety verification; and (4) an in-situ static load test was carried out, in which the roof was subjected to a uniformly distributed load for assessment of its structural response and to validate the results from the numerical model. Overall, this study showed that the vaulted roof of the water reservoir has sufficient load capacity for its future use. Moreover, this work illustrates the application of a comprehensive methodology to assess the structural safety of a historical and very particular type of construction.

Mortar Characterization of Historical Masonry Damaged by Riverbank Failure: The Case of Lungarno Torrigiani (Florence)

The research of structural masonry associated with geo-hydrological hazards in Cultural Heritage is a multidisciplinary issue, requiring consideration of several aspects including the characterization of used materials. On 25 May 2016, loss of water from the subterranean pipes and of the aqueduct caused an Arno riverbank failure damaging a 100 m long portion of the historical embankment wall of Lungarno Torrigiani in Florence. The historical masonry was built from 1854–1855 by Giuseppe Poggi and represents a historical example of an engineering approach to riverbank construction, composed of a scarp massive wall on foundation piles, with a rubble masonry internal core. The failure event caused only a cusp-shaped deformation to the wall without any shattering or toppling. A complete characterization of the mortars was performed to identify the technologies, raw materials and state of conservation in order to understand why the wall has not collapsed. Indeed, the mortars utilized influenced the structural behavior of masonry, and their characterization was fundamental to improve the knowledge of mechanical properties of civil architectural heritage walls. Therefore, the aim of this research was to analyze the mortars from mineralogical–petrographic, physical and mechanical points of view, to evaluate the contribution of the materials to damage events. Moreover, the results of this study helped to identify compatible project solutions for the installation of hydraulically and statically functional structures to contain the riverbank.

Numerical Evaluation of Transverse Steel Connector Strengthening Effect on the Behavior of Rubble Stone Masonry Walls under Compression Using a Particle Model

The structural rehabilitation of historic/traditional rubble masonry wall constructions requires consolidation and retrofitting solutions to be employed in order to withstand dynamic loads, high vertical loads, and differential settlements. One of these strengthening techniques is based on the use of steel bar connectors perpendicular to the wall, considered individually or integrated into more complex strengthening techniques. The aim of this study is to evaluate numerically the strengthening effect of transverse steel connectors on rubble masonry walls. With this purpose, a 2D particle-reinforced model (2D-PMR) was devised and applied to model uniaxial compression tests. The results presented show that predictions calculated using the proposed 2D-PMR model are very close to known experimental results, particularly in the corresponding failure modes, the increase of the maximum uniaxial compression value, and ductility. Parametric studies are also conducted by varying the diameter of the steel bars and the level of strengthening to assess the influence of the bar-bond effect and lateral plates. The presented parametric numerical studies show that (i) a two-level strengthening solution guarantees a similar response to the three-level strengthening solution adopted in the experiments; (ii) it is not relevant to apply a grout injection during the application process of the steel connectors if lateral plates are adopted; and (iii) the 2D-PMR model can be used in the definition of the steel bar diameter and properties; as shown, a smaller (8 mm) bar diameter predicts a similar strengthening effect to the (12 mm) bar size adopted in the experiments. Given the performance of the proposed 2D-PMR model, further work is underway that will allow the 2D-PMR model to numerically assess other reinforcement techniques, namely, reinforced micro-concrete layers and textile reinforced mortar.

Assessment of properties of rubble masonry used in heritage structure

Preservation of Heritage structures is of utmost importance. Rubble masonry played a significant role in the conservation of structures. It is a traditional wall construction material used to build walls and standing structures in India since ancient times. Even now, heritage structures are being made to serve humanity for many years. Therefore, it is necessary to find a combination of rubble masonry and essential additives like lime mortar and surkhi to help build new heritage structures and also help reduce the deterioration of ancient architectural structures and monuments. This experimental study presents rubble masonry for repairing Heritage structures as an alternative to the conventional use of cement mortar. In addition to repairing work, rubble masonry, lime mortar, and surkhi are used to build new heritage structures for long-term sustainability. Rubble masonry, lime mortar, and surkhi can reduce the deterioration of old architectural structures and monuments. A case study on Global Vipassana Pagoda allocated in Mumbai, India, is considered. It is made up of Basalt stone with an interlocking system.

Effect of the vertical component of ground motion on a rubble masonry wall model

In this paper the influence of the vertical component of ground motion on the performance of an unreinforced masonry wall is analysed using sets of one-component and two-component ground motions. The set of motions represents the actual seismicity of L'Aquila, while the investigated wall mimics an experimental specimen with two unconnected external leaves and a rubble core. The model falls within the mixed finite element method – discrete element method and accounts for crack formation, complete separation and new contact formation. The modelling strategy is capable to simulate the out-of-plane seismic response and the progressive loss of compactness of the wall up to collapse with the separation between the two external leaves. The vertical component increases the fragility of the wall and confirms the relevance of vertical ground motion for very vulnerable constructions. Nonetheless, to worsen the response, the vertical component needs to overcome specific, non-negligible intensity measure thresholds.

The Behaviour of Load-Carrying Members from Cordwood

With the growing importance of sustainable construction in the world, cordwood is gaining additional interest as a building material for load-bearing structures. The number of studies on cordwood is limited; there is a lack of information on cordwood design methods, including in the case of fire exposure. The design methods for axially compressed load-carrying cordwood members, including in the case of fire action, are described and supplied by the numerical examples. Numerical and laboratory experiments are carried out to clarify the behaviour of cordwood under pressure with different types of binder. For the analysis of cordwood’s load-bearing capacity, the equivalent composite material (rubble masonry) calculation method is proposed. The analytical method for designing cordwood in the case of fire action is based on a combination of the reduced cross-section method and the 500 isotherm method. It is stated that the use of low- or medium-high-strength mortar (up to 10 MPa) for cordwood is the most rational and economical. Additionally, it is shown that 40 cm thick cordwood could be used as a material for load-carrying walls for two-storey buildings and provide very high fire resistance—R180, in the case of a double-sided fire action.

Nonlinear Seismic Assessment of a Historic Rubble Masonry Building via Simplified and Advanced Computational Approaches

This research presents a comprehensive nonlinear quasi-static seismic assessment of an unreinforced rubble masonry building, Bytown Museum in Ottawa, Canada, using discontinuum-based analyses. In the proposed modeling approach, non-uniform geometrical properties of rubble masonry walls are replicated via a group of rigid polyhedral blocks interacting along their boundaries based on the discrete element method (DEM). Once the adopted modeling strategy is validated, the nonlinear quasi-static analysis of the South and North façades of the Bytown Museum is performed. Special attention is given to the irregular block generation within the discontinuum analysis framework, where discrete element models are generated from high-resolution site recording data, representing the masonry morphology at a high level of detail. Then, the predicted collapse mechanisms from advanced computational models are further utilized to generate pre-defined macro-blocks in kinematic limit analyses, providing a simple alternative solution for seismic assessment. The results reveal the significant effect of openings and the construction technique (morphology) in unreinforced rubble masonry buildings that can play an important role in the structural capacity and behavior. Moreover, it is noted that DEM-based solutions provide lower seismic capacity compared to kinematic limit analyses. Finally, a noticeable sensitivity to the input parameters in the discrete element models is noted; therefore, characterization of material properties is necessary for reliable predictions.

Machine-learning for damage assessment of rubble stone masonry piers based on crack patterns

Under seismic actions, stone masonry buildings are prone to damage. To assess the severity of damaged masonry buildings and their failure modes, engineers connect these problems to surface crack features, such as the crack width and the extent of cracking. We aim to further these assessments in this study, wherein we propose using simple machine learning models to predict: 1) three ratios encoding the degradation of stiffness, strength, and displacement capacity of damaged rubble stone masonry piers as a function of the observed crack features and the applied axial load and shear span ratio; and 2) the pre-peak vs. post-peak regime, based on the crack features.When predicting the stiffness, force, and drift ratios, the prediction error is significantly reduced when the axial load and shear span ratio are included in the feature vector. Furthermore, when predicting the pre-peak vs. post-peak regime, simple machine learning models such as the k-nearest neighbor and the logistic regression result in remarkable accuracy.The obtained results have significant implications on the automated post-earthquake assessment of masonry buildings using image data. It is shown based on documented laboratory test data, that, by selecting proper crack features and incorporating information about the kinematic and static boundary conditions, even simple machine learning models can predict accurately the damage level caused to a rubble masonry pier. The three crack features used in this study are the maximum crack width, length density, and complexity dimension. The pipeline developed in this paper is general enough and is applicable to other masonry typologies and elements upon new evaluation of crack features and image data.

Seismic retrofitting of rubble masonry tunnel: evaluation of steel fiber shotcrete or inner concrete lining alternatives

Seismic retrofitting of rubble masonry tunnel: evaluation of steel fiber shotcrete or inner concrete lining alternatives

A Hybrid Particle/Finite Element Model with Surface Roughness for Stone Masonry Analysis

Circular and spherical particle models are a class of discrete elements (DEM) that have been increasingly applied to fracture studies of quasi-brittle materials, such as rock and concrete, due to their proven ability to simulate fracture processes through random particle assemblies representing quasi-brittle materials at the grain scale. More recently, DEM models have been applied to old stone masonry fracture studies. In order to extend its applicability to structures of larger dimensions, an enhanced hybrid particle model is proposed here that allows finite elements with a given surface roughness, provided by the discretization of the element boundary with particles, to interact with the particulate media in which they are embedded. The performance of the hybrid model is compared with that of a traditional all-particle model under uniaxial testing. It is shown that similar results are obtained, namely, in the elastic phase, figures of rupture and pre-peak and post-peak behavior, while the hybrid model allows for a significant computational run time reduction of 20% to 25% in the coarse particle assemblies. Finally, the proposed hybrid model is applied in the simulation of shear tests of stone masonry walls and dry and mortared joints, providing reasonably good agreement with both the experimental results and predictions. For the rubble masonry tests, the hybrid model allows for a computation run time reduction of around 40% when compared with an all-particle model.

Seismic behaviour of rubble masonry: Shake table test and numerical modelling

AbstractThe destruction of Amatrice and the surrounding villages in Central Italy after the 2016 seismic sequence was so impressive that engineers, authorities and local communities started sharing the common feeling that historical stone masonry buildings were too below current safety standards. The severe damage caused by the earthquakes led to a general distrust of traditional building techniques, leading to the conclusion that there is nothing to do but demolish and rebuild, perhaps with a false antique. Is there an alternative? Is there a way to combine safety and preservation of architectural heritage? This paper aims contributing to the understanding of the seismic behaviour of stone masonry by reproducing, through simulation on a shake table, the progressive loss of compactness of a real scale rubble masonry wall up to the ruinous collapse with the separation between the two external leaves. The laboratory simulation allowed to evaluate the decrease of the fundamental frequency with increasing damage and estimate the maximum displacement profile and the amount of cracking that the wall is able to sustain before failing. Eventually, two modelling strategies based on finite and discrete element methods were proposed and applied to verify the capability of simulating the out‐of‐plane seismic response and the failure mechanisms of rubble masonry.

A new non-invasive method for the seismic retrofit of rubble masonry using composite connectors

A new non-invasive method for the seismic retrofit of rubble masonry using composite connectors

Hygrothermal modelling of historic rubble masonry walls: Accounting for geometric and compositional variability

An established issue when assessing the hygrothermal performance of heritage buildings is the correlation between measured data and model outputs. This can be attributed to many factors including climate data and hygrothermal material property data. Two overlooked factors are the variation in geometry and level of decay in the structure. This can be true for several historic wall assemblies with irregular geometries and elevated levels of decay. There is a lack of guidance on how and when to incorporate this into a hygrothermal model. The goal of this paper is to examine how this variability in geometry and composition may affect model outcomes using a simulation approach with stochastic methods for a sample rubble core masonry wall.Geometrically stochastic models were generated from a script accounting for varying levels of air voids in the wall and irregular stone patterns. The presence of voids alters heat, capillary and vapour transport. This was combined with hygrothermally dissimilar mortar and stone units. Simulations were performed under four boundary conditions: heat, drying, wetting and actual weather data. The results showed that geometric stochasticity can lead to a large variation of results. The presence of voids in the wall also led to a reduction in heat and moisture transport in the assemblies. The results of the stochastic simulations were then compared to a set of simplified one and two-dimensional models to judge their appropriateness. It was found that 2-D parallel like models that account for the mortar joint in some fashion are most appropriate.

Determination of Manning's Roughness Coefficient in Bijayapur Irrigation Canal, Kaski, Nepal

The discharge in irrigation canal is to be determined for the proper allocation of water to the fields as per the crop-water requirement. Manning’s roughness coefficient is one of the major important parameters for estimating discharge in open channel. The purpose of this research is to determine Manning’s roughness coefficient in open channel flow by means of measuring velocity, cross-section, bed slope using Manning’s equation. It also discusses how it varies along with various aspects of channel geometry and draws useful conclusion from the analysis. The investigation was carried out in the Bijayapur Irrigation System which is situated in Kaski district of Nepal. The velocity was measured using current-meter and discharge was calculated from the area velocity methods. Roughness coefficient was calculated using the Manning’s equations for the uniform flow in open channel. The average value of Manning’s roughness coefficient at Sakneri and Bijayapur computed from this study was found 0.028 and 0.037, respectively. The roughness coefficient, however, being a parameter representing the integrated effects of the channel cross-sectional resistance, the result of this study shows the higher value of roughness coefficient for the material (cement rubble masonry) used in the construction of canal. The higher value of roughness coefficient might be due to uneven bed and poor condition of banks as observed during the study. The greater value of roughness coefficient definitely reduces discharge which leads to the tail end deprivation in the command area.

Determination of Manning's Roughness Coefficient in Bijayapur Irrigation Canal, Kaski, Nepal

The discharge in irrigation canal is to be determined for the proper allocation of water to the fields as per the crop-water requirement. Manning’s roughness coefficient is one of the major important parameters for estimating discharge in open channel. The purpose of this research is to determine Manning’s roughness coefficient in open channel flow by means of measuring velocity, cross-section, bed slope using Manning’s equation. It also discusses how it varies along with various aspects of channel geometry and draws useful conclusion from the analysis. The investigation was carried out in the Bijayapur Irrigation System which is situated in Kaski district of Nepal. The velocity was measured using current-meter and discharge was calculated from the area velocity methods. Roughness coefficient was calculated using the Manning’s equations for the uniform flow in open channel. The average value of Manning’s roughness coefficient at Sakneri and Bijayapur computed from this study was found 0.028 and 0.037, respectively. The roughness coefficient, however, being a parameter representing the integrated effects of the channel cross-sectional resistance, the result of this study shows the higher value of roughness coefficient for the material (cement rubble masonry) used in the construction of canal. The higher value of roughness coefficient might be due to uneven bed and poor condition of banks as observed during the study. The greater value of roughness coefficient definitely reduces discharge which leads to the tail end deprivation in the command area.

Low-impact techniques for seismic strengthening fair faced masonry walls

Two techniques for the seismic strengthening of fair faced rubble masonry walls are proposed and tested on a shake table. The first solution entails the use of carbon fibre reinforced polymer connectors installed from outside through the natural stone units, without perforating the entire wall thickness, thus leaving the internal wall surface undisturbed. In the second solution, stainless-steel cords are embedded in repointed mortar joints of the fair face and connected, by means of stainless-steel bars, to a thermo-insulating composite reinforced mortar applied to the internal side. Shake table tests were performed under natural accelerograms on real scale multi-leaf rubble masonry walls, built with the stone units retrieved from the debris of a hamlet heavily damaged in the 2016 Central Italy earthquakes. Both strengthening solutions proved effective in enhancing the seismic capacity by preventing leaf separation and masonry disintegration, and in limiting damage development under earthquake excitation. Thanks to the compatibility with original materials and the preservation of the fair face, they are suitable for mitigating the seismic vulnerability of architectural heritage.