Structural damages of L'Aquila (Italy) earthquake

On 6 April 2009 an earthquake of magnitude 6.3 occurred in L'Aquila city, Italy. In the city center and surrounding villages many masonry and reinforced concrete (RC) buildings were heavily damaged or collapsed. After the earthquake, the inspection carried out in the region provided relevant results concerning the quality of the materials, method of construction and the performance of the structures. The region was initially inhabited in the 13th century and has many historic structures. The main structural materials are unreinforced masonry (URM) composed of rubble stone, brick, and hollow clay tile. Masonry units suffered the worst damage. Wood flooring systems and corrugated steel roofs are common in URM buildings. Moreover, unconfined gable walls, excessive wall thicknesses without connection with each other are among the most common deficiencies of poorly constructed masonry structures. These walls caused an increase in earthquake loads. The quality of the materials and the construction were not in accordance with the standards. On the other hand, several modern, non-ductile concrete frame buildings have collapsed. Poor concrete quality and poor reinforcement detailing caused damage in reinforced concrete structures. Furthermore, many structural deficiencies such as non-ductile detailing, strong beams-weak columns and were commonly observed. In this paper, reasons why the buildings were damaged in the 6 April 2009 earthquake in L'Aquila, Italy are given. Some suggestions are made to prevent such disasters in the future

Investigation of the Characteristics of the Boron Doped MnO Films Deposited by Spray Pyrolysis Method

Boron doped MnO films were prepared by spray pyrolysis technique at 375°C substrate temperature, which is a low cost and large area technique to be well-suited for the manufacture of solar cells, using boric acid (H₃BO₃) as dopant source, and their properties were investigated as a function of doping concentration. Boron doping was achieved by adding 0.1 M, 0.2 M, 0.3 M, and 0.4 M H₃BO₃ to the starting solution. X-ray analysis showed that the films were polycrystalline fitting well with a cubic structure and have preferred orientation in (111), (220) and (311) directions. Optical band gap of the undoped and B-doped MnO films were found to vary from 2.25 to 2.54 eV. The changes observed in the energy band gap and structural properties of the films related to the boric acid concentration are discussed in detail