The assessment of the out-of-plane response of unreinforced masonry (URM) buildings with cavity walls has been a popular topic in regions such as Central and Northern Europe, Australia, New Zealand, China and several other countries.Cavity walls are particularly vulnerable as the out-of-plane capacity of each individual leaf is significantly smaller than the one of a solid wall. In the Netherlands, cavity walls are characterized by an inner load-bearing leaf of calcium silicate bricks, and by an outer veneer of clay bricks that has only aesthetic and insulation functions. The two leaves are typically connected by means of metallic ties. This paper utilizes the results of an experimental campaign conducted by the authors to calibrate a hysteretic model that represents the axial cyclic response of cavity wall tie connections. The proposednumerical 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 the strength degradation, the unloading stiffness degradation and the pinching behaviour. The numerical modelling approach in this paper can be easily adopted by practitioner engineers who aim to model the wall ties more accurately when assessing the structures against earthquakes.
Energy dissipative steel cushions (EDSCs) are simple units that can be used to join structural members. They can absorb a substantial amount of seismic energy due to their geometric shapes and the ductile behavior of mild steel. Large deformation capability and stable hysteretic behavior were obtained in monotonic and cyclic tests of EDSCs in the framework of the SAFECLADDING project. Discrete numerical modeling strategies were applied to reproduce the experimental results. The first and second models comprise two-dimensional shell elements and one-dimensional flexural frame elements, respectively. The uncertain points in the preparation of the models included the mesh density, representation of the material properties, and interaction between contacting surfaces. A zero-length nonlinear link element was used in the third attempt in the numerical modeling. Parameters are recommended for the Ramberg–Osgood and bilinear models. The obtained results indicate that all of the numerical models can reproduce the response, and the stiffness, strength, and unloading and reloading curves were fitted accurately.
Climate change adaptation has influenced river management through an anticipatory governance paradigm. As such, futures and the power of knowing the future has become increasingly influential in water management. Yet, multiple future imaginaries co-exist, where some are more dominant that others. In this PhD research, I focus on deconstructing the future making process in climate change adaptation by asking ‘What river imaginaries exist and what future imaginaries dominate climate change adaptation in riverine infrastructure projects of the Meuse and Magdalena river?’. I firstly explore existing river imaginaries in a case study of the river Meuse. Secondly, I explore imaginaries as materialised in numerical models for the Meuse and Magdalena river. Thirdly, I explore the integration and negotiation of imaginaries in participatory modelling practices in the Magdalena river. Fourthly, I explore contesting and alternative imaginaries and look at how these are mobilised in climate change adaptation for the Magdalena and Meuse river. Multiple concepts stemming from Science and Technology Studies and Political Ecology will guide me to theorise the case study findings. Finally, I reflect on my own positionality in action-research which will be an iterative process of learning and unlearning while navigating between the natural and social sciences.
The Ph.D. candidate will investigate the seismic response of connection details frequently used in traditional Dutch construction practice, specifically in the Groningen area. The research will focus on the experimental and numerical definition of the complete load-deflection behaviour of each considered connection; specifically, the tests will aim at identifying stiffness, strength, ductility, and dissipative behaviour of the connections. The experiments will be conducted on scaled or full-scale components that properly resemble the as-built and retrofitted as well connection details. The tests will involve monotonic and cyclic loading protocols to be able to define the load and displacement response of the connection to reversal loads, such as earthquakes, as well as the development of failure mechanisms under such loading cases. Possibly, also dynamic tests will be performed. Numerical models will be created and calibrated versus the experimental findings. Characteristic hysteretic behaviours of the examined connection types will be provided for the use of engineers and researchers.
