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In the Netherlands a program for the enhancement of quality in the restoration of monumental buildings is presently carried out, stimulated by national authorities and coordinated by the foundation ERM. Guidelines are issued by the branches involved, from architects to masons, under guidance of an experts’ committee, to perform interventions on monuments and assess them. The aim of this paper is to discuss the contributions to the program offered by different actors active in the field of conservation, the existing synergies and the potential of using a common language and approach. These are needed to facilitate communication and exchange knowledge. The use of the terminology of MDCS (Monument Diagnosis and Conservation System) can help create a community of stakeholders. Sharing the damage terminology and methodology can help achieving a clear and systematic assessment of damage and its causes. It can further improve the communication among all stakeholders, including owners and laymen, stimulating cooperation, and can allow monitoring of damage and interventions.

In recent years, the seismic risk in the north of the Netherlands has increased due to gas extraction. Since 2014, the Delft University of Technology started a research program to assess the seismic response of unreinforced masonry (URM) buildings. The Dutch URM buildings are characterized by slender piers and transverse walls. In common practice, the connections between piers and transverse walls are often modelled as rigid, but in real structures these connections may exhibit different behaviour. Especially, since the 1980s, calcium silicate element masonry has been commonly used in Dutch buildings, and vertical continuous joints are present between transverse walls. For this reason, it appears essential to assess the connection strength properties, since its failure can significantly reduce the seismic performance of the entire structure. The first part of this work investigates and compares different numerical approaches to describe the nonlinear behaviour of masonry under lateral loads, simulating seismic action. The second part specifically focuses on the critical issues related to the modelling of vertical connections of Dutch URM buildings. A sensitivity study of the frictional parameters is performed to analyze the influence of the strength of the glued connection on the global response of the URM structure.

The degree of similarity between damage patterns often correlates with the likelihood of having similar damage causes. Therefore, deciding whether crack patterns are similar is one of the key steps in assessing the conditions of masonry structures. To our knowledge, no literature has been published regarding masonry crack pattern similarity measures that would correlate well with assessment by structural engineers. Hence, currently, similarity assessments are solely performed by experts and require considerable time and effort. Moreover, it is expensive, limited by the availability of experts, and yields only qualitative answers. In this work, we propose an automated approach that has the potential to overcome the above shortcomings and perform comparably with experts. At its core is a deep neural network embedding that can be used to calculate a numerical distance between crack patterns on comparable façades. The embedding is obtained from fitting a deep neural network to perform a classification task; i.e., to predict the crack pattern archetype label from a crack pattern image. The network is fitted to synthetic crack patterns simulated using a statistics-based approach proposed in this work. The simulation process can account for important crack pattern characteristics such as crack location, orientation, and length. The embedding transforms a crack pattern (raster image) into a 64-dimensional real-valued vector space where the closeness between two vectors is calculated as the cosine of their angle. The proposed approach is tested on 2D façades with and without openings, and with synthetic crack patterns that consist of a single crack and multiple cracks.

Prefabricated concrete piles have been used for the foundation of bigger buildings for about a century. Often a change in function, an addition (also vertically) or another type of alteration is required, resulting in different loads on the foundation. There are several complicating factors that return regularly in these assessments. The first one is a lack of data. Often drawings are missing or incomplete, e.g. showing only pile head dimensions or maximum calculated load but not the pile length, pile tip shape or material properties. Inspection is hard and only possible for the part directly under the pile head. And a third complication is that in The Netherlands there have only been official codes for piles since 1992. Various calculation and design methods from WWII until 1985 are discussed to see if there is any consistency that might lead to an indication of the load bearing capacity of piles in The Netherlands from that era. It is concluded that design rules for the load bearing capacity of concrete pile foundations in The Netherlands have been inconsistent over time. If the original detailed geotechnical calculations and/or structural drawings cannot be found in archives then the given ultimate loads cannot only not be exceeded; even if the load on a pile is currently less than stated on the technical specifications designers are advised not to increase the load.

Historic concrete buildings (end of 19th century – 1960s), because of their “experimental” character, require a specific approach to both survey and conservation. Although they were built with empirical approaches, some buildings show a fair state of conservation and resilience –even though they have already exceeded the 100-year threshold– while others of comparable age are in severe need of restoration. As part of the European project CONSECH20, aimed at contributing to the conservation of cultural-heritage concrete buildings, this paper investigates what are the most common types of damage and hypothetical causes, and what direct and non-direct parameters can lead to a faster or slower deterioration of historic concrete in the Netherlands. The research is based on an initial screening study, which will be used as a basis for a larger research among the participant countries. The current research is divided in three phases. Firstly, a selection of 15 case studies from the Netherlands are investigated; the selection was based on criteria of age, state of conservation and type of ownership. Secondly, the history and materials of the buildings are examined. Thirdly, an on-site visual survey is performed per each building, with pre-design templates, to identify types of damage, extent and severity. The data is then analysed combining different factors with a calculated index of severity. Results are discussed and contrasted to provide further clarification of the degradation of historic concrete. A fourth phase, not discussed in this paper, will use this methodology in a broader context, with a larger number of case studies in different countries.

In the last two decades, the province of Groningen, located in the North-East of the Netherlands, has been subjected to an increasing number of earthquakes induced by gas extractions. The existing building stock is mainly composed by unreinforced masonry (URM) buildings not conceived to resist seismic loads. The need of reducing the vulnerability of these buildings by means of retrofit interventions, led to the development and adoption of a new guideline (NPR9998:2018). As regards the seismic assessment of URM buildings using nonlinear static analysis, the guideline includes significant differences with respect to Eurocode 8, which is adopted in other European countries. The more significant differences lay in the description of failure mechanisms and constitutive laws of piers and spandrels, in the identification of limit states and in the calculation of seismic demand. In the last years, the assessment and retrofit in the region has been carried out using software based on an equivalent-frame strategy: among these, the 3Muri software has been widely adopted. The solver of this program is the research software TREMURI. In this work, a new version of the solver adopted by the software 3Muri, complying with the requirements of the new Dutch guideline, was developed; the tool was then validated with simple examples. To illustrate the specificities of the new guideline, the seismic assessment of a building representative of one of the most widely diffused URM building typologies in the area was performed.

The wall of Casa Salvans is a masonry arched and buttressed retaining wall which was built in 1909 and located in Terrassa, Catalonia. It contains a series of 11 arches of unique shapes, dimensions and inclinations that are supported on buttresses. Despite being a common retaining wall typology, it can be very challenging to assess the stability of such structures given the variability of their geometry. As such, a systematic methodology for the stability assessment of such walls was developed and applied to the case of the wall of Casa Salvans. Self-produced photogrammetry survey enabled creating accurate three-dimensional models of the front of the wall that were later combined with available information from a topographic survey to build cross sections of the wall for analysis. Modern retaining wall design principles evaluating the stability against overturning and sliding were used to assess the condition of the wall. As a consequence of the uncertainties related to the soil parameters and buried elements of the wall, the stability factors could not comply with modern design criterion. Some parametric analyses were carried out on the shear strength parameters of the backfill, revealing that slight increases in the soil internal friction and wall friction angles enhance the stability factors significantly. Since reasonable soil internal and wall friction angles justifying the stability of the wall were obtained, carrying out a geotechnical survey to determine the actual values was recommended. The in-plane stability of the arches was also verified according to the Lower Bound Theorem by locating a thrust line that fits within all the boundaries despite very conservative geometric assumptions.

Churches are part of heritage structures that take an important role in Europe ́s cultural identity. As such, these structures must be protected to prevent catastrophic collapse and any damage must be reported timely to establish planning to maintenance and restoration. This can be achievable when the churches are monitored periodically with regular intervals. However, this monitoring strategy has not been available in most of the Europe’s churches for a number of reasons, complexity of the structures and limited budget are just two of them. Laser scanning has been widely used in capturing rich three-dimensional (3D) topographic data of visible surfaces of a structure with high accuracy. This paper presents a methodology to determine the shape and possible deviation from verticality of the church’s tower for monitoring deformation using a terrestrial laser scanner. The 500-year old wooden tower of St. Bavo Church in Haarlem, Netherlands is selected as a case study. First, point clouds of the tower captured from different views are registered into the same coordinate system. Second, a RANSAC method is employed to extract point clouds of a whole façades of the tower. Next, a point and surface-based method is proposed to compute the deformation of the surface from its data points. The results indicate that there is slightly different deformation between the tower facades in the same story and in neighbour stories. Moreover, the maximum total relative deformation at Story 7 of the tower by 0.63m.

Bed joint reinforced repointing is a strengthening method often used in the Netherlands to counteract settlement damage. This strengthening technique consists of cutting a slot in the mortar joint and installing twisted steel bars embedded in a high-strength repair mortar. Due to the increase in seismic activities, triggered by gas extraction in the region of Groningen (northern part of the Netherlands), it is of interest to investigate whether this strengthening technique is efficient against seismic load. In order to characterize the performance of the bed joint reinforced repointing using twisted steel bars, an experimental campaign was conducted at Delft University of Technology. A quasi-static cyclic in-plane test on a full-scale wall was performed; similar tests on unstrengthened specimens were available from a previous experimental campaign [1][2] and were used for comparison. Moreover, small scale pull-out tests were performed to study the interaction between the steel bars and the repair mortar. By comparing the response of unstrengthened and strengthened masonry specimens, it is observed that the use of bed joint reinforced repointing can provide an increase in terms of ductility and displacement capacity, but not in terms of force capacity. Regarding the serviceability limit state, a reduction in crack width and an increase of load at onset of cracking were observed. The preliminary information obtained for the presented case study provides the ground for futher research as well as benchmark for numerical modelling.

This paper explores a novel restoration approach for consolidating historic structures using structural glass to substitute for the missing elements, preserving at the same time the structural integrity of the structure. A restoration design is proposed for the hypothetical consolidation of the remaining tower of Schaesberg Castle, in Limburg, The Netherlands. The masonry walls suffer from a significant loss of material and a temporary steel structure currently prevents the tower from collapsing. It is proposed to use stacked float glass to fill the missing parts of the wall. The connection between the old masonry and new glass is the most challenging aspect given the different physical and mechanical properties of the materials, which need to work together in a coherent way. Shear tests of various connecting materials are carried out in order to evaluate the performance of this connection with respect to aspects of compatibility and feasibility.

En este documento se presenta un estudio sobre el diseño y la construcción de depósitos de ferrocemento para países en vías de desarrollo. Se le da un especial énfasis al hecho de que los depósitos que se plantean están pensados para países en vías de desarrollo, porque la tecnología empleada así como los materiales tendrá una calidad notablemente inferior a la que se podría esperar de países desarrollados. Asimismo, la participación de los usuarios (a través de la supervisión de un técnico) en la construcción del depósito hace que se tienda a simplificar lo máximo posible el montaje de la estructura así como la cantidad de cálculos necesarios. En primer lugar se introduce el concepto de ferrocemento, se analizan sus propiedades, se describen sus componentes (tipo de refuerzo, proporciones de mezcla,…), se detallan algunos elementos empleados para su ejecución (encofrado, herramientas, equipo necesario,…) y se hace un breve repaso, a continuación, a las aplicaciones que hasta la fecha se le han dado al ferrocemento como material de construcción. También se incluyen los resultados correspondientes a unos ensayos realizados en un estudio sobre el diseño de tanques para países en vías de desarrollo (llevados a cabo en otra universidad) y obtenidos a través de Internet. A continuación se plantea una formulación específica para el dimensionamiento de la pared del depósito y se acompaña con algunos ejemplos de aplicación práctica en base a la formulación planteada que recogen capacidades bien diferenciadas: 10, 50 y 150m3. De este modo se recogen los diseños tipo para un depósito pequeño, mediano y grande (considerando el ámbito en el que nos encontramos y el rango en el que se mueven este tipo de estructuras). En éstos se resuelve el diseño de la solera a través de un exhaustivo análisis por Elementos Finitos de diversos modelos de solera, considerando como forma básica el casquete esférico y variando a partir de aquí la curvatura de éste así como la unión con la base de la pared. Al final de cada ejemplo propuesto se muestra un croquis detallado de la estructura, el refuerzo y las cotas correspondientes. Se incluye también un capítulo con ejemplos reales sobre depósitos de ferrocemento (concretamente se comentan la construcción de un depósito de 10m3, uno de 150m3, un depósito enterrado y el montaje de una cubierta para un tanque de ferrocemento) fruto del trabajo de investigación bibliográfica llevado a cabo a lo largo del estudio y que se ha creído conveniente incluir por su alto interés técnico. Los ejemplos además se acompañan de los detalles y mediciones de las obras. En una segunda parte, se generalizan los resultados para un rango de depósitos acotado entre un cierto valor de alturas y radios del depósito. El rango adoptado es bastante amplio, variando el radio desde 50cm hasta 10m, mientras que las alturas consideradas van de 1m hasta 3m. Se abarca, de esta manera cualquier posibilidad de dimensionamiento, por muy remota que sea. El criterio adoptado a la hora de acotar el rango de los resultados ha sido el de proporcionar alturas razonables para facilitar la construcción y diámetros no mayores de los que parece ser que este material llega a resultar más viable que otro como por ejemplo el hormigón (aunque este tema es discutible). Estos resultados se han resumido a modo de tablas organizadas según las variables estudiadas sean variables de dimensionamiento (capacidad, espesores, cuantías de armadura, flecha de solera) o de cuantificación de materiales (peso de acero, volumen de arena, peso de cemento), dando lugar en total a 12 tablas, cuyo método de empleo se describe en el propio capítulo. Además para tener una idea comparativa de los resultados ofrecidos por las tablas se analizan diversos ejemplos comparando las cantidades propuestos por diversos autores y los obtenidos a partir del empleo de las tablas. Cabe destacar que estas tablas no pretenden ser un método estricto, sino más bien orientativo (en fase experimental), en el que se recomienda al menos la presencia de un técnico para valorar los resultados y apreciar los detalles necesarios que lógicamente no se incluyen en las tablas como herramientas, elementos de atado, encofrado, personal necesario, etc.

Tunnel construction can cause deformations of the surrounding ground, which endanger buildings and other structures located in the vicinity of the tunnel. The prediction of these deformations and the damages to the buildings is difficult due to limited knowledge of the geotechnical conditions and uncertainty in the response of the structures to the settlements. This paper presents a probabilistic model for prediction of the damage to buildings due to tunneling, which combines the volume loss method with the equivalent beam model. It furthermore proposes a probability-based method for determination of the limiting value of settlement that is used for control purposes during the tunnel construction. Updating of the limiting settlement with measurements gathered during the construction is described. The proposed methodology is applied to a masonry building affected by the construction of the L9 metro line tunnel in Barcelona.

Tunnel construction can cause deformations of the surrounding ground, which endanger buildings and other structures located in the vicinity of the tunnel. The prediction of these deformations and the damages to the buildings is difficult due to limited knowledge of the geotechnical conditions and uncertainty in the response of the structures to the settlements. This paper presents a probabilistic model for prediction of the damage to buildings due to tunneling, which combines the volume loss method with the equivalent beam model. It furthermore proposes a probability-based method for determination of the limiting value of settlement that is used for control purposes during the tunnel construction. Updating of the limiting settlement with measurements gathered during the construction is described. The proposed methodology is applied to a masonry building affected by the construction of the L9 metro line tunnel in Barcelona.