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The main objective of the National Seismic Network for Constructions, operated by the National Institute for Research and Development in Constructions, Urban Planning and Spatial Territorial Development “URBAN-INCERC”, is the monitoring of situations generated by earthquakes or other dangerous sources of vibrations induced in constructions on the entire Romanian territory. The NIRD URBAN-INCERC seismic records obtained in-situ and on buildings were and are extremely important for designers, especially in 1977, 1986 and 1990. It is the largest network in Romania, consisting of some 60 digital acceleration recorders distributed in Bucharest and in the country. This network is strategic from the population safety point of view. Due to the specific seismic hazard and vulnerability, our country shall be in preparation for the impact of a possible earthquake, which cannot be predicted in time domain, but it is possible to occur anytime. To prevent and mitigate negative consequences of such an event, urgent actions are required to ensure structural safety. Given the facts, Romania is in a critical time on strategic options regarding the seismic risks.

The stations from the INCD URBAN-INCERC network are distributed throughout the country, including Bucharest, and are located either in free-field conditions, in small buildings, in medium-height buildings or in boreholes. The interactive map representation of the seismic stations and the automatic monitoring of their operation, based on the analysis of received data, are currently carried out with the SeisComP software. The paper exemplifies, as performance benchmarks, some data processing obtained in 2022 within the permanent seismic monitoring system. [ABSTRACT FROM AUTHOR]

The paper presents the current level in the development of an integrated system to ensure the security of the built space, with semi-automatic generation of PGA maps from seismic actions or other vibrating sources and rapid assessment of the vulnerability of instrumented/monitored buildings. The integrated and automated system is an essential step for the early detection of damage to future earthquakes. As performance benchmarks are listed: identification and acquisition of specialized software, an instrumentation campaign of public utility buildings belonging to NIRDs at national level, some case studies. The obtained results are transferable and of special technical and legal importance, the elaborated documents representing the basis for the Technical Book, and the archived data constituting initial records for the future data obtained after a major earthquake. Finding a reliable solution for a quick analysis after an earthquake, by generating a report with the dynamic parameters of the monitored buildings behaviour, is a challenge of a strategic and logistical nature, of acquisition, storage and continuous processing of data, elaboration of analytical models for validation, in context of digital approach for structural engineering. [ABSTRACT FROM AUTHOR]

The fire security of buildings can be increased by the decrease of fire propagation intensity resulting from compartment fires and by using sustainable building enveloping solutions, with the role of limiting the spread of fires to neighboring floors and adjacent buildings. In this regard, research in the international literature highlights the need of conducting large-scale fire tests on the thermal insulation of buildings. The researchers from INCERC Bucharest have configured and adapted, for the first time in Romania, a large-scale stand designed to perform experimental tests to evaluate the fire resistance behavior of External Thermal Insulation Composite Systems (ETICS). The fire testing stand was designed following the analysis of fire resistance testing concepts of ETICS systems at European level. [ABSTRACT FROM AUTHOR]

The paper presents an assessment approach based on non-destructive and temporary vibration monitoring methods of a reinforced concrete building which is to be structurally and thermally rehabilitated. These methods are in according to the Romanian Code for Seismic Design of Building, Part 3 - Building Assessment, SR EN 1998-3:2008. The results related on dynamic characteristics of this building obtained by ambient vibration monitoring with a data acquisition system are presented. Also, a solution for the thermal insulation of the building is presented, as well as some results obtained from fire testing of this type of system. Where it is not possible to obtain correct information regarding the behaviour of a structural system, due to the lack of data needed to create a reliable model, the contribution of each presented method is consistent, using the advantages of non-destructive methods, ambient vibration monitoring and modal analysis. It is a current internationally practice, with a certain confidence. [ABSTRACT FROM AUTHOR]

Vibrations caused by some industrial sources (forges, presses etc.) are transmitted to the ground, generating different surface waves, with significant effects on building foundations, as well as some effects on buildings and their occupants. The structural dynamic response to this type of vibration also depends on the phenomenon of structure-soil interaction and the phenomenon of attenuation/amplification of vibrations. The principle of the applied method consists in determining the actual values of the characteristic parameters from the recorded vibrations in-situ /in building, in order to verify the fulfilment of the velocity criteria which are correlated with certain degrees of damage. In view of the means of controlling vibrations (at source, by transmission and in remote buildings) with physical or on human perception effects, the made assessments will determine whether the prevailing frequency produced by industrial equipment, within the monitored activities, is finds itself in the area of adjacent buildings' frequencies, with possible effects on the comfort of the inhabitants. The article aims to present comparatively the results obtained from the some instrumented sites. [ABSTRACT FROM AUTHOR]

The dynamic analysis is based on a simplified model for the seismic action, structural system and the soil, but it should be correlated with the techniques of experimental investigation of vibrations generated by various seismic/non-seismic sources. Currently, the limitations of equipment are reduced, there is modern equipment of last generation and the buildings can be monitored from distance and the data can be transmitted to users or to research institutes in the field through a system of transmitting data in real time. As a case study, an existing building is presented, to get the natural vibration modes; these vibration modes will be validated by the values obtained from the micro seismic instrumentation. A comment on range of vibration frequency for the studied building, as possibly obtained also in the case of strong seismic motion, will be done. It is very important to be established if from recordings data, the structural response to micro seismic actions consists always in frequencies corresponding to the natural vibration modes and, in the case of another type of motion, the dynamic characteristics will be the same. [ABSTRACT FROM AUTHOR]

The paper is intended to present some aspects regarding the safety evaluation methods by determining those defining characteristics of a structural system (behaviour in time through dynamic characteristics evolution). This assessment should first be initiated in the case of buildings with essential functions and which could pose a major threat to public safety in case of collapse or serious damage. Determining, using intelligent wireless sensor networks, used within of a real-time data transmissions system, of some accelerograph data obtained from earthquakes with significant magnitude, will lead to an image of the spatial distribution of peak ground acceleration (PGA). Obtaining additional data over time will highlight some conclusions about acceleration values and directivity of seismic waves in the territory. On the other hand, the determination of the dynamic characteristics of structural systems by non-invasive and non-destructive instrumental measurements, under normal micro-seismic agitation, offers the possibility of obtaining important data in the structural safety assessment process after a major earthquake. Correlation of structural dynamic information, determined in situ and by analytical approaches, is a necessary step in the continuous process of risk exposure in an area with disaster potential. Data about a few study cases are presented. [ABSTRACT FROM AUTHOR]

Dense seismic instrumentation and modern devices are a prerequisite to making accurate observations on seismicity and its effects on buildings. In-situ instrumental data contribute to a correct understanding of the importance and of the influence of various factors on the structural dynamic response, as well as their correlation with interest objectives for the building owners/beneficiary. Romanian experience in INCERC after 1977 has demonstrated that damage to buildings was correlated with some changes in the oscillation periods of buildings. This distinction serves to decouple the influences that these Vrancea seismic motions have exercised successively and/or cumulative on the damage state. The rigidity and the values of oscillation periods are influenced not only by visible degradation, but also by a series of deformations and invisible cracks, accumulated in the building structure, which may be significant. In this regard, the determination of the dynamic characteristics of building structures is one of the most important aspects of structural health monitoring. [ABSTRACT FROM AUTHOR]

The paper presents the analysis of collapse and damage state to some special buildings during recent severe surface earthquakes, The presented irregular reinforced concrete buildings (with irregular distributions of mass, stiffness, strength, geometrical configurations), especially the setback structures and tall structures, have exhibited a poor seismic performance. Through graphical representations of response spectra obtained from records, it is revealed that most of the damage occurred to buildings due to exceeding the code requirements, the level of accelerations and to the spectral composition, unusual to the surface earthquakes, which justify the shown interest. Comparative analysis of numerical data is shown in order to put into evidence the effects of surface earthquakes on buildings. It must be accepted that an important role in the overall behaviour of the presented buildings had the higher modes of vibration and shaking time, beyond the technical aspects. What is noticeable, also, are the long periods of motions, although the earthquakes are of surface. The more accelerograms recorded are, we find that the possible values may be higher than those from design codes and sometimes the codes provisions are taken from other design rules (with other local features). [ABSTRACT FROM AUTHOR]

Copyright of Constructii is the property of General Association of Engineers in Romania and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Constructii is the property of General Association of Engineers in Romania and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)