Andreas Stavridis

After the 2017 Puebla‐Morelos earthquake, the Applied Technology Council (ATC) funded a mission to Mexico City to collect structural, geotechnical, seismological, and damage information on concrete structures. The collected data set includes 70 reinforced concrete buildings and contains photos, design drawings, ground motion records, ambient vibration data, and reconnaissance observations, where available. This article presents the most important structural observations and instrumentation findings. The data show that, in buildings with a flexible lateral system, the unreinforced masonry infill walls resisted substantial load and prevented more severe damage to the structural system. Many previously retrofitted buildings failed in locally unreinforced areas, because retrofits did not comprehensively strengthen all weaknesses in the building. Significant damage was also observed in buildings with weak story irregularities and buildings founded on weak soil.

This article presents the Applied Technology Council (ATC) team’s observations following the 2017 M _w 7.1 Puebla–Morelos, Mexico earthquake. The team was deployed in Mexico City to collect seismological, geotechnical, structural, and overall performance information. The focus was on non‐ductile concrete structures, to support implementation of recently published FEMA P‐2018 procedures and to identify study buildings for incorporation into NIST‐funded ATC‐134 ongoing project. This article presents seismological data with 71 strong‐motion records processed and ready for use in engineering analysis, geotechnical observations, and characterization of sites visited. Analyses of the response of representative soil profiles are presented in the form of acceleration response spectra and seismic amplification at the ground surface. A comparison of the same analysis using records from the 1985 Michoacán M _s 8.1 (approximately M _w 8.0) earthquake is also discussed. The ATC team composed GIS maps with structural and geotechnical characteristics of the inspected sites, including color‐coded damage of inspected buildings and estimated soil fundamental period to correlate observed behavior with potential soil–structure interaction resonance effects. Recommendations on further detailed studies based on this comprehensive set of case histories are proposed.

Summary: This paper discusses the dynamic tests of a two‐story infilled reinforced concrete (RC) frame building using an eccentric‐mass shaker. The building, located in El Centro, CA, was substantially damaged prior to the tests due to the seismic activity in the area. During the testing sequence, five infill walls were removed to introduce additional damage states and to investigate the changes in the dynamic properties and the nonlinear response of the building to the induced excitations. The accelerations and displacements of the structure under the forced and ambient vibrations were recorded through an array of sensors, while lidar scans were obtained to document the damage. The test data provide insight into the nonlinear response of an actual building and the change of its resonant frequencies and operational shapes due to varying damage levels and changes of the excitation amplitude, frequency, and orientation.

Tunnel fires are low-probability high-consequence events that could lead to loss of lives, property damage, and long service disruptions. The rapid rise of gas temperature in excess of 1000 °C within the confined tunnel space can affect the structural integrity of the tunnel. Although tunnel fires may not necessarily cause collapse, significant structural damage and disruption to rail services can lead to major economic losses. The objective of this paper is to investigate the expected structural damage in a cut-and-cover tunnel if exposed to a fire event. The analyses are completed by numerical simulations. In the first part of this work, the effects of fire scenario and variability in thermal properties of material, on the potential volume of damaged tunnel lining that would require repair are investigated. In case of tunnels, historical events show that limited accessibility to suppress the fire can cause the fire to burn for days. The fire scenarios considered in this work are defined based on (a) the worst-case envelop hydrocarbon fires such as the Rijswaterstaat (RWS) fire curve and the RABT ZTV fire curve, and (b) the potential heat release rates in railway tunnels. In the second part of this study, the effect of fire scenario on structural performance of a cut-and-cover tunnel is studied. The geometry and cross section of the Howard street tunnel in Baltimore that experienced a major fire in 2001 is used as the case study. The results show that the fire scenario and duration, while contains significant uncertainty, is one of the most influential factors on evaluating response of the tunnel structures.