Experimental Ductility of Compression-Controlled Flexural Members Using CFRP Grid to Confine Concrete

Concrete members are typically designed so that flexural failure initiates with steel yielding and ends with concrete crushing in compression in order to take advantage of the yielding property of steel that allows for large deformations prior to any fracture of the material. On the other hand, if a large percentage of steel or linear elastic non-yielding reinforcement (i.e., FRP composite) is used, the member flexural failure typically initiates and ends with concrete crushing in compression. These members are known as compression-controlled members and typically exhibit brittle behavior. This study proposes a new approach in improving the flexural behavior of over-reinforced members through concrete confinement using carbon fiber reinforced polymer (CFRP) grid tubes in the compression zone. The concept was experimentally tested using rectangular beams. Beam 1 (control beam) had no grid reinforcement and beam 2 (tube beam) had two 152 mm grid tubes embedded in its compression zone. Experimental results indicate improvement in the ductility of the tube beam compared to the control beam of approximately 20–30% depending on the criteria used. Considering the low amount and mechanical properties of the CFRP grid, the improvement is significant, which shows that the proposed approach is valid and improves the ductility of compression-controlled members.

Optimized Planning of Distribution Grids Considering Grid Expansion, Battery Systems and Dynamic Curtailment

The increasing integration of renewable energies into the grid is calling for the expansion of the power transport capacities in the distribution system. Yet, the expansion of the grid could require long authorization procedures and cannot be always asserted. Therefore, a higher utilization of the existing grid is becoming increasingly necessary today. This paper proposes a new time series-based planning method for distribution systems using classical grid expansion instruments as well as innovative planning instruments such as battery storage systems (BSS) and dynamic power curtailment (DPC). These planning instruments could be applied individually or combined. The aim of the BSS and DPC application is to enable a higher utilization of the grid at minimal costs. The proposed method, which has been implemented as an automated planning algorithm, determines the cost-optimal grid reinforcement measures that ensure the prevention of prognosticated congestions in the considered grid. Furthermore, the application of the proposed planning method on the considered power system has proven that a combination of BSS and grid expansion could be more economical than an individual application of BSS and grid expansion.

Thermal and Seismic Capacity Improvements for Masonry Building Heritage: A Unified Retrofitting System

Today, the attention in the retrofitting of building is quickly growing. In this field, the re-use of waste materials and the innovation in the retrofitting techniques are among the crucial topics. Generally, thermal capacity and seismic resistance are two aspects very felt by the building owners. Commonly, independent approaches are assessed in order to cover the energy and mechanical lacks of a building. In such a way, the intervention may result time- and cost-consuming or, sometimes, poorly effective. The present paper aimed to propose and validate a new retrofitting system based on the partial use of waste materials, such as fly ash and expanded glass (acting as a matrix), and a fiber open grid reinforcement. The proposal is suitable for the plastering of building with the double scope of thermal insulation and seismic strengthening throughout a unique application. An experimental investigation was carried out considering small-scaled masonry panels with double-side retrofitting. The studied parameters were thermal transmittance and shear strength. The results evidenced the effectiveness of the proposed technique, able to significantly improve the un-retrofitted masonry, from both the thermal and mechanical point of view.

Storage Placement and Sizing in a Distribution Grid with High PV Generation

With the increasing penetration of renewable resources into the low-voltage distribution grid, the demand for alternatives to grid reinforcement measures has risen. One possible solution is the use of battery systems to balance the power flow at crucial locations in the grid. Hereby, the optimal location and size of the system have to be determined in regard to investment and its effect on grid stability. In this paper, the optimal placement and sizing of battery storage systems for grid stabilization in a small low-voltage distribution grid in southern Germany with high PV penetration are investigated and compared to a grid heuristic reinforcement strategy.