This paper outlines the common observed failure patterns in the buildings of Nepal after M_W 7.8 Gorkha (Nepal) earthquake. Several types of damage patterns were observed for reinforced concrete buildings, as well as for unreinforced masonry and adobe houses during the reconnaissance survey performed immediately after the earthquake of 25 April 2015. Several field visits in the affected districts were conducted and associated failure/damage patterns have been identified and analyzed. This paper also covers damage patterns in non-engineered buildings, middle and high-rise buildings, commercial complexes, administrative buildings, schools and other critical facilities from Kathmandu valley as well as other affected districts. The construction and structural deficiencies are identified as the major causes of failure, however local soil amplification, foundation problems, liquefaction associated damages and local settlement related damages are also significantly observed during this earthquake and reported in the present paper. In the end, the lessons learned from the field survey are resumed in order to give some guidelines for future construction practices.

In structural analyses, masonry infill walls are commonly considered to be non structural elements. However, the response of reinforced concrete buildings to earthquake loads can be substantially affected by the influence of infill walls. In this article, an improved numerical model for the simulation of the behavior of masonry infill walls subjected to earthquake loads is proposed and analyzed. First, the proposed model is presented. This is an upgrading of the equivalent bi-diagonal compression strut model, commonly used for the nonlinear behavior of infill masonry panels subjected to cyclic loads. Second, the main results of the calibration analyses obtained with two series of experimental tests are presented and discussed: one on a single frame with one story and one bay tested at the LNEC Laboratory; and the second, on a full-scale four story and three-bay frame tested at the ELSA laboratory.

In this study, the implementation of an optical accelerometer unit based on fiber Bragg gratings, suitable to monitor structures with frequencies up to 45 Hz, is reported. The developed optical system was used to estimate the structure eigenfrequencies of a steel footbridge, with a total length of 300 m, over the Sao Pedro Creek, located at University of Aveiro Campus, in Portugal. The acceleration records measured with this solution are compared with those obtained by traditional commercial electronic devices, revealing a root-mean-square error of 2.53 times 10^-5 G.