The research concentrated on a behavior of the deep composite deck ComFlor210 under a concentrated force. The distribution of a concentrated force in ComFlor210 was studied numerically and analytically.
The finite element model of a composite slab with 5.4m span showed good agreement with test results in the elastic stage. The parametric study of composite slab ComFlor210 revealed that in a slab with span 3.2m and 5.4m the load is distributed over three middle ribs. In a slab with 7.2m span, the load was spread over all five ribs. The bending resistance of the rib was exceeded for slab with 7.2m span.
In the elastic part of the load-deflection curve, the variation in cross-sectional properties causes a minor change in a slab response.
The proposed engineering model was unable to predict the deflection of the composite slab under concentrated load with the desired accuracy.
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Sustainability concerns steer the construction sector towards adopting a circular economy philosophy. Steel-concrete composite beams are extensively used in multi-story buildings and bridges due to their competitive construction and efficient material use. Currently the composite action is mainly achieved by headed shear connectors welded to the top flange of the beam, obstructing the non-destructive demountability. Demountable shear connectors can be used in order to open up the composite con-struction for reusability. Demountable shear connectors can take the form of a bolted connection which requires a tight control of construction tolerances. This thesis is fo-cused on studying a bolt coupler connector which is seen as a valuable alternative to the more conventional embedded bolt. The proposed shear connector consists of a bolt and coupler embedded in prefabricated concrete decks which are connected through the top flange of the steel section by an injection bolt.
Full-scale experiments have been performed to investigate the feasibility of construc-tion of a demountable car park. The demountable flooring was obtained by large pre-fabricated concrete decks in combination with tapered beams. Experimental research has confirmed the possibility of assembly and disassembly of the system if construction tolerances are appropriately designed. The most influential factors were quantified based on experimental observations, measurements and finite element models. The hole clearance should be designed keeping in mind the deformability of the system during construction, the manufacturing tolerances and the speed of construction. Experiments show that resin injection can be reliably and labour efficiently used for large oversized holes which allow for higher fabrication imperfections and reduced construction while at the same time enabling composite action of the connectors under live load.
The reusability of the structure was confirmed by a set of eight four-point bending tests considering uniform and non-uniform connector arrangements. Finite element models closely match the experimental results in terms of deflection, stresses and curva-ture. However, the end slip is overpredicted which is in line with research performed by other authors. The efficiency of the non-uniform connector arrangements was studied experimentally and numerically to reduce the construction costs. Concentrating the shear connectors toward the supports will bring the highest benefit in terms of beam bending stiffness without the need of a large number of connectors to prevent uplift.
An extensive cost analysis was performed based on a database of 15500 beam solu-tions generated by a design algorithm develop as part of this thesis. The case study provides a preliminary cost assessment of two demountable steel-concrete composite floorings in order to quantify their economic viability. It was shown that the system constructed with prefabricated solid slabs is more viable compared to the demountable profiled sheeting slab. The most influential contribution to the final cost of the struc-ture comes from the steel work and the labour intensive manufacturing.
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The increase of the human-induced seismicity in the Groningen has increased the interest of all stakeholders to ensure the structural safety of all residents in the affected area. While there are already many conventional structural strengthening methods that are proposed and being implemented in the affected area, the study of a new innovative strengthening method by using an active control system is attractive and intriguing. The current structural upgrading strategies mainly focus on improving the structural strength and stiffness of the load bearing elements. The active control, on the other hand, could provide an additional dissipative energy mechanism to any building by counteracting the damaging force by the control force produced by the actuators.

The effectiveness of the active control is assessed with multiple time history seismic events in the Groningen area to see the robustness of the control system against seismic excitations with various characteristics. Checking of the structural response with consideration of Significant Damage Limit State is conducted. The control goal is to prevent significant damage of the structure so that the cost of repair, demolishing, or even re-construction of new dwellings could be reduced or even prevented. The terraced house is modelled as a single residential unit by a 2D finite element model. Only the façade wall is analysed as the terraced house is vulnerable in the out-of-plane direction and in a direction parallel to the façade wall because the façade piers are considerably narrow.

The active control application is realized by putting a steel truss at each façade wall that is connected by pneumatic cylinder actuators. The control strategy follows the closed-loop control scheme where the control force is calculated based on the feedback of the structural response. The control force is calculated by the Linear Quadratic Regulator (LQR) algorithm. The structure needs to be represented into a state-space representation for the LQR algorithm to calculate the control force. The structural response is solved by the Newmark Beta numerical integration. The time delay effect is also taken into account to consider a more accurate representation of the actual system. Simplified soil-structure interaction cases are also studied to see the effect of the soil conditions towards the control performance. Eventually, the preliminary dimensioning of the steel truss and the pneumatic cylinders is conducted to see the practicability to provide a small scale and realizable control system. ... Read more

This master thesis covers the research into cracking behaviour of slender high strength concrete cantilevering balconies. The research emerged from Pieters Bouwtechniek Delft and Hi-Con Denmark. They cooperatively designed very slender balconies in ultra-high performance fibre reinforced concrete. Other engineering firms tend to recreate these balconies in HSC and insecurities emerged around the cracking behaviour and crack width prediction for these slender HSC cantilevering balconies. In addition to this research an informative report, also functioning as a literature study, on the connection of prefabricated concrete balconies is produced. This report is separately attached.

The research is step wisely conducted starting with a simple fully clamped cantilevering slab. For this slab the cross sectional height, reinforcement diameter and reinforcement spacing are varied to investigate their influence on analytical crack width predictions. First for all variants an analytical design and analysis process is executed, followed by a numerical analysis with DIANA FEA and a comparison of the results. The most important observation is that for a cross sectional height of 120 mm or smaller reinforcement bars are located outside the effective area, making the analytical method unsuitable. Furthermore, a big discrepancy between the predictions of the different analytical models is observed, indicating an unreliability of these methods.

In two steps the fully clamped balcony is transformed into a Hi-con shaped balcony executed in HSC. It appeared that in light of detailing rules from Eurocode 2 an exact reproduction is impossible, but the concept could be reproduced in a less slender way. Furthermore, by comparing analytical and numerical design results for two different balcony designs it is found that the accuracy of the analytical crack width prediction depends on geometric disturbances. In case a geometric disturbance is present in a slender area loaded in tension peak stress concentrations occur, which negatively influence the reliability of the analytical crack width prediction. In case the area is less slender, the effect is less pronounced and the conservative characteristics of the analytical method outweigh the influence of the concentrated peak stresses.

When summarizing, it appears that specific care should be taken when analytically predicting crack widths in slender balconies because it might appear that the reinforcement is not located in the effective area. Furthermore, the more slender the structures become, the bigger the influence of a geometric disturbance can be, increasing the risk of an underestimation of the occurring crack widths because peak stress concentrations are analytically not accounted for.
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