Bio-Based Composite Bridge – Lessons Learned

The concept and design process of the world’s first bio-based composite pedestrian bridge at the campus of Eindhoven University of Technology was described and presented at the previous IASS conference in Tokyo [1], [2]. The bridge has a span of 14 m and uses a bio-composite as the main structural material, which is based on hemp, flax and Greenpoxy. In the meantime the project has been successfully realized and finished in November 2016.\u3cbr/\u3eThe focus of this paper will be on a couple of major aspects, that can be helpful for future projects using bio-based composite materials: evaluation of the material tests, comparison of the FEM analysis with the 1:1 scale load test, production process as well as the monitoring of the bridge after installation. In order to understand the material properties in a better way a series of tests have been and still are being conducted in the laboratory at TU/e. Apart from the prior essential tests, such as strength and stiffness, further ongoing tests look at the creep behaviour of the composite material. The installation of the bridge was carried out in public space, so full approval of the authorities had to be obtained. Due to the fact that no building codes exist for bio-based composite materials the authors had to prove the correctness of their calculations with a full scale load test. At the moment the longterm behaviour of the bridge is monitored with in total 27 fibre-optical sensors to further study and evaluate the strain properties over a period of 1 year with varying environmental conditions. It can be concluded that bio-based composite materials show a great potential for applications in the built environment, while also a long list of questions remains for researcher to be answered

Demolition versus transformation, mortality of building structures depending on their technical building properties

\u3cp\u3eThis paper describes the assessment of 60 multi-story buildings in the Netherlands, the followed approach and the main results. The 60 buildings have been assessed on their technical building properties to see which building parameters could be influential on the probability of an elongated Service Life for the building structure. The buildings, (of which 40 buildings have been given a Second Life through Transformation and 20 buildings have been demolished) have been assessed, initially on 64 different parameters. The number of parameters has then been reduced to 20, more or less influential parameters. A quick scan of building structures has been derived from these parameters. This quick scan uses an aggregated value expressing the re-use potential in a single adaptability/flexibility score. In a similar approach as often is used in medical survival analysis, the Mortality of Buildings have been calculated for different Flexibility Scores. Further elaboration will make it possible to assess building structures and then give an indication on their probability for (future) transformation. This is important, not only to assess our existing building stock but also to improve elongated Service Live's for new buildings. By optimizing the Service Life of buildings structures, negative material impacts can be further reduced and the Re-use and Transformation on building level, rather than on material level, can be improved. More realistic Service Life Estimations will make comparisons of different solutions with different levels of Flexibility much more feasible.\u3c/p\u3

Fully bio-based-composite footbridge : strain monitoring during use phase

Last year a bio based pedestrian bridge, first in its kind, has been installed at the TU/e University campus in Eindhoven. Material test formed the basis for the innovative design and the research project resulted in the production and installation of the bridge. Because there are still a lot of unknowns in the material behaviour of the used bio-composites, it was decided to monitor and test the bridge further after production. For this purpose optical FBG sensors have been installed. The FBG sensors show the material strains in good detail and the results of the thus measured strains in load tests are shown. The test results are compared with results from earlier material tests. The short term structural behaviour follows closely the used elastic models based on calculated as well as measured stiffnesses. The long term time dependent behaviour however shows a number of different influences from creep, temperature and moisture content that can not yet be fully explained by earlier measurements and tests

Shape memory alloys for seismic retrofitting of social housing in an integrate perspective

Traditional buildings are conceived as a set of different construction layers with different roles, thus generating complex information to coordinate during rehabilitation and retrofitting. When architectural features are not a concern, such as in most of the social housing heritage, a new external envelope can be superimposed to the building in order to solve, with a single intervention, functional, architectural and, in particular, seismic problems. The new structure, connected to the existing building with shape memory alloys-based seismic devices, can prevent collapses and dissipate horizontal loads granting a calibrated operability. This paper shows the feasibility of the proposal through the numerical results of nonlinear static and dynamic analyses applied to two structural typologies, namely masonry and concrete frame with masonry infill, in different seismic zones. Finally, the method is verified for a real case study

Seismic isolation for existing masonry houses in Groningen/ NL combined with thermal upgrading

Induced earthquakes, caused by the winning of natural Gas in the North of the Netherlands (Groningen province), are causing significant damage to the existing, often relatively weak, masonry buildings. This seismic hazard and seismic rehabilitation problem in the Groningen area involves much more than just a technical seismic safety problem. Many different stakeholders are involved, not in the least the local population, attached to their local environment and their often privately owned houses. The proposed seismic rehabilitation method can preserve and improve these masonry housing units, by combining seismic isolation with thermal insulation. Core of the approach is applying seismic base isolation by removing the existing, often poor quality, timber floor structure, and, making new foundation footings with a new thermal insulated structural (reinforced concrete) ground floor. First calculations indicate that the rehabilitation method can significantly reduce the seismic impact and seismic hazard of these existing masonry houses

Mechanical characterization of a shape morphing smart composite with embedded shape memory alloys in a shape memory polymer matrix

This article presents a smart composite that shows a reversible bending deformation from an initial flat configuration into a 90° angle controlled by local thermal activation. The novelty lies within the structural fixation of the deformation at room temperature without continuous energy input. The new structural architecture of antagonistic performing shape memory alloy actuators embedded in a shape memory polymer matrix is presented. The shape memory polymer is locally heated from the rigid glassy state to the easily deformable rubbery state by integrated heating wires. By subsequent activation of the different shape memory alloy actuators by resistive heating, the reversible performance can be realized. By deactivation of the heating wires in the shape memory polymer, the shape memory polymer fixates the deformation in its rigid condition. The actuation characteristics of the smart composite are investigated by thermo-mechanical experiments. The performance of the smart composite was investigated by thermo-mechanical experimentation of the individual components. The results show that a 90° bending deformation is feasible with the current material dimensions, but repeated deformation is restricted due to fatigue of the alloy. By superposition of the bending forces of the individual components, it is possible to estimate the bending angle of the composite material

Adaptive liquid lens and sunlight redirection

The paper describes a novel system to alter and redirect sunlight under large roofs with the help of a liquid lens system. Focus lies on the computational design, testing, measurement and evaluation of the performance of a physical prototype. The results in terms of daylight and illumination of the interior, as well as the possibility for sunlight redirection, lead to an array of adaptive natural light spotlights, which are rather promising. The journal article is an extension of previously reported work[1]

Ultra-lightweight space frame structures based on minimal path computation

Minimal surfaces, as visible in various natural systems, have great potential for application in high-rise building design, due to their structural efficiency, overall area minimization, and efficient material distribution. All of these factors contribute to a sustainable architectural model and green building concept as they integrate structure, form and force distribution in one coherent system. In architecture, minimal surfaces have been predominantly realized as tension-active surface structures, namely membranes or cable-nets [4]. Their application for compression active-structures, other than shells, has not been as prominent. On the other hand, many examples exist in nature. As natural systems are able to compute, in essence, their physical form is the result of a constant feedback process. In this research, we model the formations of soap film to derive a space frame structure based on minimal paths. The system is then applied to the design of a 500m tall prototypical steel structure. The three-dimensional space frame structure was created using minimization methods and shortest path algorithms. Together with horizontal slabs, it forms a rigid system which can be seen as an alternative to conventional structural solutions in high-rise building design. First simulations indicate that these systems can achieve the same stiffness with less material compared to traditional space frame structures based on 90 degree angles. The proposed system is an ultra-light structure design that allows for minimal material usage, thereby reducing the environmental impact significantly without compromising the structural integrity of more conservative solutions

Review of Seismic Retrofitting Strategies for Residential Buildings in an International Context

After increasingly strong earthquakes in the Groningen area in the north of the Netherlands, which are induced by gas extraction, the Dutch government decided to cut output from the gas field as well as upgrade existing houses in this region. Due to the fact, that it is expected, that the frequency as well as magnitude of these earthquakes will rise, the development of structural upgrading strategies plays a major role in this context and a review of possible measurements from other countries has been carried out and will be described within this paper.\u3cbr/\u3eThe study includes a review of various building codes and general information about seismic resistant buildings in “earthquake-experienced” regions, namely California, Italy and New Zealand. Further on different structural materials, building techniques and seismic retrofitting methods, which are used for residential buildings, will be\u3cbr/\u3econsidered. Most of the affected houses in the region in and around Groningen are masonry structures, which are vulnerable to seismic loading. This requires a thorough understanding of the structural behavior and performance in order to develop appropriate strengthening and upgrading strategies for them. Based on the experience from other\u3cbr/\u3ecountries various design proposals will be suggested to improve the durability of the existing housing stock in the Groningen area