Zoekresultaten

Walking between houses, Paul Julien in Sudan

April 2015 Sudanese photographer Elsadig Mohamed and I tried to relate the photographs that Paul Julien made when traveling through the country in 1933 and 1948 to stories and realities alive in present day Sudan. This initial research was pretty successful and we thought a first presentation of the work done was in place to see how a Sudanese audience would respond to our attempts. The exhibition was installed in a minimum amount of time. There were hundreds of people (estimates range between 5 and 9 hundred) at the opening. Whether they came for the photographs or for the concert that took place outside of the museum we will never know. People did show an interest in what was on the wall and we will continue towards next presentations both in and outside of Sudan.Walking Between Houses, the title of the Sudanese part of the larger Paul Julien project is titled ‘Walking Between Houses’. This is part of a Sudanese proverb, referring to the in between place as the source of knowledge. The photographs Julien made in Sudan can be found on this Facebook page. A film impression of the exhibition with responses of visitors was made by Rhea Schmitt for the Goethe Institute in Khartoum.

Experimental characterisation and mechanical modelling of connection details in traditional Groningen houses

Post-earthquake structural damage shows that out-of-plane wall collapse is one of the most prevalent failure mechanisms in unreinforced masonry (URM) buildings. This issue is particularly critical in Groningen, a province located in the northern part of the Netherlands, where low-intensity ground shaking has occurred since 1991 due to gas extraction. The majority of buildings in this area are constructed using URM and were not designed to withstand earthquakes, as the area had never been affected by tectonic seismic activity before. Hence, the assessment of URM buildings in the Groningen province has become of high relevance.Out-of-plane failure mechanisms in brick masonry structures often stem from poor wall-to-wall, wall-to-floor or wall-to-roof connections that provide insufficient restraint and boundary conditions. Therefore, studying the mechanical behaviour of such connections is of prime importance for understanding and preventing damages and collapses in URM structures. Specifically, buildings with double-leaf cavity walls constitute a large portion of the building stock in the Groningen area. The connections of the leaves in cavity walls, which consist of metallic ties, are expected to play an important role. Regarding the wall-to-floor connections, the traditional way for URM structures in Dutch construction practice is either a simple masonry pocket connection or a hook anchor as-built connection, which are expected to be vulnerable to out-of-plane excitation. However, until now, little research has been carried out to characterise the seismic behaviour of connections between structural elements in traditional Dutch construction practice.This thesis investigates the seismic behaviour of two types of connections: wall-to-wall connections between cavity wall leaves and wall-to-floor connections between the masonry cavity wall and timber diaphragm, commonly found in traditional houses in the Groningen area. The research is divided into three phases: (1) inventory of existing buildings and connections in the Groningen area, (2) performance of experimental tests, and (3) proposal and validation of numerical and mechanical models. The thesis explores the three phases as follows:(i) An inventory of connections within URM buildings in the Groningen area is established. The inventory includes URM buildings of Groningen based on construction material, lateral load-resisting system, floor system, number of storeys, and connection details. Specific focus is given to the wall-to-wall and wall-to-floor connections in each URM building. The thickness of cavity wall leaves, the air gap between the leaves and the size and spacing of timber joists are key aspects of the inventory.(ii) Experimental tests are performed on the most common connection typologies identified in the inventory. This phase consists of two distinct experimental campaigns:o The first experimental campaign took place at the laboratory of the Delft University of Technology to provide a comprehensive characterisation of the axial behaviour of traditional metal tie connections in cavity walls. The campaign included a wide range of variations, such as two embedment lengths, four pre-compression levels, two different tie geometries, and five different testing protocols, including both monotonic and cyclic loading. The experimental results showed that the capacity of the wall tie connection is strongly influenced by the embedment length and the tie geometry, whereas the applied pre-compression and the loading rate do not have a significant influence.o The second experimental campaign has been carried out at the laboratory of the Hanze University of Applied Sciences to characterise the seismic behaviour of timber joist-masonry cavity wall connections, reproducing both as-built and strengthened conditions. Twenty-two unreinforced masonry wallets were tested, with different configurations, including two tie distributions, two pre-compression levels, two different as-built connections, and two different strengthening solutions. The experimental results highlighted the importance of cohesion and friction between joist and masonry since the type of failure mechanism (sliding of the joist or rocking failure of the masonry wallet) depends on the value of these two parameters. Additionally, the interaction between the joist and the wallet and the uplift of the latter activated due to rocking led to an arching effect that increased friction at the interface between the joist and the masonry. Consequently, the arching effect enhanced the force capacity of the connection.(iii) Mechanical and numerical models are proposed and validated against the performed experiments or other benchmarks. Mechanical and numerical models for the cavity wall tie and mechanical models for the timber joist-masonry connections were developed and verified by the experimental results to predict the failure mode and the strength capacity of the examined connections in URM buildings.o The mechanical model for the cavity wall tie connections considers six possible failures, namely tie failure, cone break-out failure, pull-out failure, buckling failure, piercing failure and punching failure. The mechanical model is able to capture the mean peak force and the failure mode obtained from the tests. After being calibrated against the available experiments, the proposed mechanical model is used to predict the performance of untested configurations by means of parametric analyses, including higher strength of mortar for calcium silicate brick masonry, different cavity depth, different tie embedment depth, and the use of solid bricks in place of perforated clay bricks.o The results of the experimental campaign on cavity wall ties were also utilised to calibrate a hysteretic numerical model representing the cyclic axial response of cavity wall tie connections. The proposed model uses zero-length elements implemented in OpenSees with the Pinching4 constitutive model to account for the compression-tension cyclic behaviour of the ties. The numerical model is able to capture important aspects of the tie response, such as strength degradation, unloading stiffness degradation, and pinching behaviour. The mechanical and numerical modelling approach can be easily adopted by practitioner engineers seeking to model the wall ties more accurately when assessing URM structures against earthquakes.o The mechanical model of timber-masonry connections examines two different failure modes: joist-sliding failure mode, including joist-to-wall interaction and rocking failure mode due to joist movement. Both mechanical models have been validated against the outcomes of the experimental campaigns conducted on the corresponding connections. The mechanical model is able to estimate each contribution of the studied mechanism. Structural engineers can use the mechanical model to predict the capacity of the connection for the studied failure modes.This research study can contribute to a better understanding of typical Groningen houses in terms of identifying the most common connections used at wall-to-wall and wall-to-floor connections in cavity walls, characterising the identified connections and proposing mechanical models for the studied connections.

An energy expedition

The municipality of Apeldoorn had polled the interest among its private home-owners to turn their homes energy neutral. Based on the enthusiastic response, Apeldoorn saw the launch of the Energy Apeldoorn (#ENEXAP) in 2011. Its goal was to convert to it technically and financially possible for privately owned homes to be refurbished and to energy neutral, taking the residential needs and wishes from occupants as the starting point. The project was called an Expedition, because although the goal was clear, the road to get there wasn’t. The Expedition team comprised businesses, civil-society organisations, the local university of applied sciences, the municipality of Apeldoorn, and of course, residents in a central role. The project was supported by Platform31, as part of the Dutch government’s Energy Leap programme. The #ENEXAP involved 38 homes, spread out through Apeldoorn and surrounding villages. Even though the houses were very diverse, the group of residents was quite similar: mostly middle- aged, affluent people who highly value the environment and sustainability. An important aspect of the project was the independent and active role residents played. In collaboration with businesses and professionals, through meetings, excursions, workshops and by filling in a step- by-step plan on the website, the residents gathered information about their personal situation, the energy performance of their home and the possibilities available for them to save and generate energy themselves. Businesses were encouraged to develop an integrated approach for home-owners, and consortia were set up by businesses to develop the strategy, products and services needed to meet this demand. On top of making minimal twenty from the thirty-eight houses in the project energy neutral, the ultimate goal was to boost the local demand for energy- neutral refurbishment and encourage an appropriate supply of services, opening up the (local) market for energy neutral refurbishment. This paper will reflect on the outcomes of this collective in the period 2011-2015.

Resilient refurbishment, An assessment model for future-proof housing renovation

This article deals with the question how renovate the houses in the Netherlands with taking into account the future need for modifications.

Modeling of cavity wall metal ties for defining seismic response of Groningen houses

Expectation of floating building in Java Indonesia, case study in Semarang City

Many delta cities worldwide are dealing with the same kind of problems: rising of the sea level, land subsidence, scarcity of land and illegal housing. Multiple land use is one of these solutions that will help to reduce flooding and scarcity of land. An example of multiple land use is a floating community. This research used Semarang as location for the research into the social acceptance of floating houses. The data in this study were obtained through literature study and survey among inhabitants. The social acceptance of the inhabitants is determined with 35 respondents that have been done in the area of Kemijen, Semarang. In order to determine the social acceptance of floating houses, there are elements used, namely: knowledge of floating houses, perception of risk, urgency, implementation, chose for a floating house, requirements, positive and negative elements, self-sufficient system. According to the result of research, the social acceptance of the inhabitants is quite low, but there is potential because they see positive elements in a floating house. Low social acceptance is caused by the fact that the concept of floating houses are not well known in this community. With raising awareness on the challenges and informing the community on the possibilities on floating infrastructure will result in higher social acceptance.