Volume 16 (2021): Issue 2 (June 2021)

The shape and FRP configuration of the concrete columns can straight forwardly influence the efficiency of the FRP confinement. Most of the columns shape in concrete buildings are non-circular sections, therefore, special attention need to be given to their strengthening and rehabilitation to maintain the safety of buildings infrastructure especially, for rectangular/square sections with section depth ≥ 300mm. This paper is directed towards to this objective through an experimental investigation carried out on 8 square concrete columns having the same dimensions (300 × 300 × 1000) mm (width × depth × height respectively) with low concrete strength confined with different CFRP configurations. Two of the columns left without CFRP strengthening to be as a control specimens, two specimens were strengthened with two-layers of CFRP sheets (full confinement), two specimens were strengthened with two-layers of CFRP sheets and CFRP strips combined with CFRP anchors, in addition, one specimen was strengthened with one-layer of CFRP and CFRP strips combined with CFRP anchors, finally, the last specimen was strengthened with CFRP strips combined with CFRP anchors (partial confinement). The results revealed that CFRP composite wrapping in different confinement procedures can enhance the ultimate load capacity and ultimate compressive strength of square concrete columns having low compressive strength subjected to axial load, and the anchorage system improved based on the final failure mode of confined columns where the failure didn’t happen in the anchors zones, which was an aim of the research.

This parametric study investigates the RC Beams Rehabilitated with angle-ply composite laminate plate [θn/90m]_s. This work is based on a simple theoretical model to estimate the interfacial stresses developed between the concrete beam and the composite with taking into account the hygrothermal effect. Fibre orientation angle, effects of number of 90° layers and effects of plate thickness and length on the distributions of interfacial stress in the concrete beams reinforced with composite plates have also been studied.

One of the most important parameters necessary in the seismic force determination is the building’s fundamental vibration period, which is also useful in “health monitoring” procedure for the existent buildings, during their exploitation. The fundamental vibration period can be determined by theoretical, empirical or experimental methods. In particular, the experimental method it is known as AVT (Ambiental Vibrations Tests) procedure, which intensively studied today. In this paper it was performed a comparative analysis between fundamental vibration periods values, determined for an existent building, by using a numerical method (finite elements program - ETABS), some direct methods (empirical formulas), and an experimental method (dynamic recordings, based on AVT), using special devices as accelerometers from KINEMETRICS brad. The existent building has “house flats” destination, and it is historic monument, located in Bucharest city, which it was built in ~1930 period, and it has basement and 4 floors. The building’s structure is done half by masonry walls with concrete slabs and half by RC frames (columns and beams), with concrete slabs. The main goal of the analysis is to emphasize the advantages and disadvantages of each studied method.

Since concrete structures are subjected to degradation, one of the newly retrofitting system used to increase both the strength and the overall ductility is based on the Fibre Reinforced Cementitious Matrix (FRCM) composite material. FRCM system was proposed as an enhanced alternative to the traditional fibre reinforced polymer (FRP) jacketing, overcoming the limitations related with the use of organic adhesives. After a brief state of art about the FRCM system, the paper presents an analytical study on the confinement of plain concrete columns with FRCM composites. Representative analytical models are selected from the technical literature, and the predictions of the maximum compressive strength are compared with respect to the reference experimental results. Four plain concrete columns strengthened with FRCM system, which were previously tested by the authors, were used for this analytical study. Slightly different strength of concrete materials and different number of FRCM layers (one-layer and two-layer) differentiate the reference specimens. Therefore, the capability of the selected analytical models to make close predictions when changing the base material and the number of FRCM layers was evaluated. Recommendations are made based on the comparative results.

Statistics show that most fires occur in civil residential buildings. Most casualties are caused by the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aims to determine the physical and chemical parameters essential for the survival of persons in the early stages of a fire in different ventilation situations: with and without a mechanical ventilation system for the extraction of hot air.

These essential parameters are indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. Three full-scale experiments were carried out to study the burning behaviour. The experiments were used to calibrate and validate a numerical model with respect to the temperature variation at a specific control point inside the experimental stand. The model was further employed in order to understand the influence of the operations of the ventilation system on other active firefighting systems, fire evolution, and people evacuation. We found the ventilation system has mixed influences; we present here a detailed conclusion on its influence.