The interpretation, using methodological elements developed in INCERC, of data of instrumental nature obtained in Jassy during the 1986 and 1990 Vrancea earthquakes, is the main goal of the paper. The response spectra (for 12 azimuthally equidistant horizontal directions) of strong motion records, the global parameters which characterize an individual (horizontal) component of a record (effective peak values and corner (control) periods), and the instrumental intensity (global and averaged upon a frequency interval, based on destructiveness spectrum and on response spectrum) are the main numerical results obtained for the seismic records at hand. Finally, an evaluation of results, as well as conclusions useful for the aseismic design of buildings in Jassy, is presented.
In the next decades the design of the civil structures will be ruled by Eurocodes. For reinforced concrete structures the Eurocode2 will became of paramount importance to the design of the structural members. An important aspect of designing represents the relation between stress and strain to the design of the section for structural members. In this respect the EC2 defines 14 classes of concrete with different stress–strain relationships. The first stress–strain relation mentioned of EC2 for design is the parabola–rectangle stress distribution on concrete section, and further the simplified rectangle stress–strain shape is mentioned. Therefore, an aspect of the design, poorly emphasized in the national rule, is the design considering parabola–rectangle stress distribution on concrete section. The exposed issues in this paper concern with the design of the reinforced concrete section subjected to bending using two stress–strain relationships mentioned by EC2, and the differences are underlined. The design to bending using parabola–rectangle stress distribution for rectangular section is largely presented, and also the reliability for a fast designing is emphasized. Design relations for a parabola–rectangle stress distribution on section are mentioned. Also, aspects about the boundary between the single reinforcing domain and the double reinforcing domain are emphasized.
The main idea of meshless methods is to approximate the unknown field by a linear combination of shape functions built without having recourse to a mesh of the domain. The computational domain is discretized using a set of scattered nodes. The shape functions associated with a given node is then built considering the weight functions whose support overlaps the one of the weight function of this node; thus, there is actually no need to establish connectivities between the different nodes as in the finite element method. Monte-Carlo integration techniques are promising schemes in the context of meshless techniques. The purpose of the present paper is to implement in EFG a new body integration technique for the evaluation of the stiffness matrix that does not rely on a partition of the domain into cells, but rather points. Numerical examples based on three-dimensional elasticity problems are presented to examine the accuracy and convergence of the proposed method. In this context, Quasi-Monte Carlo integration techniques are used. The results are compared to traditional EFG. Conclusions are drawn concerning the proposed techniques and its capabilities.
The procedure Bubble Deck was applied untill now in Europe, in countries like Austria, Belgium, Denmark, Germany, Iceland, Italy, United Kingdom, Holland, also in other continents, in Canada or USA. This constructive system could not be brought into practice in so many projects achieved, only based on fundamental research to prove its validity, therefore tests were made concerning: bending behavior, reaction to shear force, the behavior of mountings, the reaction to fire, the acoustic behavior of these floors and economic analysis.
In classical art, form was considered to be reproduced in the most faithful way, representing a naturalistic reality. On the other hand, contemporary art strive to achieve its value by abstraction, and by intelectual and psychological approach. Corresponding to contextual art, the architectural rehabilitation of industrial buildings opens new paths towards form and space abstracting.
Integral bridges, or integral abutment and jointless bridges, as they are more commonly known in the USA, are constructed without any movement joints between spans or between spans and abutments. Typically these bridges have stub-type abutments supported on piles and continuous bridge deck from one embankment to the other. Foundations are usually designed to be small and flexible to facilitate horizontal movement or rocking of the support. Integrally bridges are simple or multiple span ones that have their superstructure cast integrally with their substructure. The jointless bridges cost less to construct and require less maintenance then equivalent bridges with expansion joints. Integral bridges present a challenge for load distribution calculations because the bridge deck, piers, abutments, embankments and soil must all be considered as single compliant system. This paper presents some of the important features of integral abutment and jointless bridge design and some guidelines to achieve improved design. The goal of this paper is to enhance the awareness among the engineering community to use integral abutment and jointless bridges in Romania.
Researches conducted at the Faculty of Construction in Jassy showed several factors that may help finding technical solutions which will make possible to economically apply acceleration procedures of concrete hardening by thermal treatment with solar energy. It has to be mentioned the fact that the thermal treatment do not exclude, but it is based on the acceleration methods of concrete hardening through composition with or without the usage of different additives -- plasticizer type (to reduce the quantity of water from the concrete) and accelerators for cement binding or hardening. These methods also take into account the climate where the process of hardening takes place.
This paper provides initially an overview of some general issues associated with the robustness of structures. Firstly, a brief discussion related to the progressive collapse, from its basic definition, to the inherent difficulties of understanding, analysing and mitigating this phenomenon is presented. Attention is also drawn to the potential sources of abnormal loads that should be examined when designing for progressive collapse performance. In addition, some of the design standards that have been developed, and methods for designing to progressive collapse hazards, are discussed. Finally, a numerical analysis of a four storey reinforced concrete frame structure has been carried out and the results concerning the assessment of a progressively damaged structure are presented.
Because of the economic changes from our country and also of the rapid adjusting necessity to the requirement of a market economy, it is observed a huge request for information, and especially techniques, tools, methodologies that would facilitate the managerial activity in any field. In the construction field the problem is even more serious because of specific aspects and of the traditional information system that is very stiff. Formal and bureaucratic, and this makes the adjusting process of specialist to the economic realities to be more difficult.
After realizing numerous constructions in the world, which use Bubble Deck concrete slabs with spherical gaps, valuable information were gathered, allowing a rigorous processing and systematization, with the purpose of realizing an experimental and documentary study. The paper presents some experimental programs which refer to concrete slabs with spherical gaps, existing in similar execution and loading conditions as those from a real construction; this implies the realization of a monolithic slab element at a scale of 1:1, which will be subjected to static gravitational loadings in order to determine the deformation (deflection), cracking and failing characteristics. The resultant conclusions will be used in defining the failing mechanisms, very useful in the formulation of an adequate mathematical model. The research proposed in the project offers an answer to the major objectives of the development of calculus methods and existent prescriptions of the concrete slabs with spherical gaps. The realization of the proposed objectives involves documentation activities, theoretical study, collaboration with different other partners, gathering and processing of the results obtained in laboratory and even in situ.
For more than one hundred years the construction system based on steel or composite steel -- concrete frames became one of the more utilized types of building in civil engineering domain. For an optimal dimensioning of the structure, the engineers had to found a compromise between the structural exigency for the resistance, stiffness and ductility, on one side, and architectural exigency on the other side. Three monotonic tests and nine cyclic tests according to ECCS loading procedure were carried out in Cluj Laboratory of Concrete. The tested composite columns of fully encased type were subject to a variable transverse load at one end while keeping a constant value of the axial compression force into them. An analytical interpretation is given for the calculus of column stiffness for the monotonic tests, making a comparation with the latest versions of the Eurocode 4 stiffness formula.
Depuis près d’un siècle, le système de construction basé sur des portiques en acier ou mixtes acier béton est devenu l’un des types les plus utilisés dans le domaine du génie civil. Plusieurs générations d’ingénieurs se sont préoccupées du développement des méthodes de calcul et des technologies de fabrication relatives à ces structures. En vue d’un dimensionnement optimal des structures, les ingénieurs sont tenus de trouver un compromis entre les exigences structurales de résistance, rigidité et ductilité d’une part, et les objectifs d’utilisation et de fonction relevant d’exigences architecturales d’autre part. Cette article fait une comparaison entre différents méthodes de dimensionnement des poteaux mixtes acier béton, en tenant compte des plusieurs paramètres.
The interest in the non-conventional energy resources, a consequence of the severe restrictions imposed towards pollution of any kind, arises again the interest in using solar collectors. Implanting them on the terraces of new or existent home residencies, or any kind of other buildings, means to solve a sum of engineering problems, among them being also the stages of safely designing the plane panels for collectors and the sustaining skeleton, made in steel as well as the fixing systems adopted for the interface with the building itself. The necessity of considering the maximum wind speeds actions along other dynamic effects of its turbulence is the result of a many years experience, specially if one must also think in terms of efficiency and costs both for construction and exploitation. The pattern of the wind flow field suffers intricate alterations in the proximity of these collectors placed in the vicinity of the building surface and, in these situations, it is common to test the models at a reduced scale in wind tunnels with atmospheric boundary layers. The experimental study presented in this paper was undertaken in the Laboratory of Aerodynamics of the Faculty of Construction and Building Services in Iaşi and it reveals the results and the conclusions drawn from the analysis of the wind flow over a row of collectors differently arranged in order to evaluate the wind pressure coefficients used in design.
The paper describes a calculus procedure to determine the elastic--plastic rotation capacity of steel structural members. The rotation capacity calculus is very important for the design of steel structures exposed to seismic action. The calculus procedure is based on the equivalent elastic--plastic bending moment. This calculus procedure was applied on two types of structural members (beams, columns).
This paper refers to the assessment of the performance level of a building for a given seismic hazard level. Building performance level describes the expected seismic performance given by the computation of R3 Nominal Assurance Degree to Seismic Action of the Existing Masonry Dwellings and Monumental Buildings according to the Romanian Norm P100:1992 [1], modified on 1996 with the chapters 11 and 12, until the Part 3 of P100-1:2006 [2], will be performed for the Assessment and Strengthening Structural Design of the Seismic Vulnerable, Existing Buildings, in the frame of SR EN 1998-1:2004 EC8 [3]. The framing of damages into the potential risk degrees has a social and economic impact. Assessment and retrofitting of the existing buildings have represented a huge engineering challenge as a distinct problem versus a new building design. The performance level of a vulnerable existing building shows us the expected seismic performance level due to the classified damages, the pattern of cracks, the interruption of function, the economic losses and the needed interventions, all in function of the importance class of building on next life span of use. On recommends the computation of R (R3) Nominal Assurance Degree to Seismic Action of the Vulnerable Dwellings for the assessing and strengthening design, in comparison to both norms because of the bearing conventional seismic load computed by [1], will result less than the value which will be computed by the Part 3 of P100-1:2006, i.e. the norm P100:1992 is more severe. In the case of the breakable fracture probability of the existing structural masonry members, one recommends a bigger value of ? – reduction factor unless the given values by [1] for a new structure with a high ductility, especially for the deflections calibration on the same limit state.
The concept of ductility estimates the capacity of the structural system and its components to deform prior to collapse, without a substantial loss of strength, but with an important energy amount dissipated. Consistent with the „Applied Technology Council” (ATC-34), from 1995, it was agreed that the reduction seismic response factor to decrease the design force. The purpose of this factor is to transpose the nonlinear behaviour of the structure and the energy dissipation capacity in a simplified form that can be used in the design stage. Depending on the particular structural model and the design standard the used values are different. The paper presents the characteristics of the ductility concept for the structural system. Along with this the general way of computing the reserve factor with the necessary explanations for the parameters that determine the behaviour factor are described. The purpose of this paper is to make a comparison between different international norms for the values and the distribution of the behaviour factor. The norms from the following countries are taken into consideration: the United States of America, New Zealand, Japan, Romania and the European general seismic code.
Ce qui suit représente une approche pertinente des aspects actuels du développement de Bucarest et de la perspective de la capitale de la Roumanie de devenir, en 2025, une véritable métropole. Dans la premiere partie de cette étude la metropole est définie en tant qu’une localité qui a plus de 200,000 habitants, qui est directement connectée au continent européen (aéroport international) et qui attire des institutions internationales et des activités multinationales de production abstraite (services représentés par des banques, des quartiers généraux et des filiales de grandes compagnies, etc.) et de production concrete (industrie d’excellence). Si l’on envisage les objectifs stratégiques de développement de chaque localité, compte tenu du niveau d’évolution, Bucarest se remarque par: a) un sous-dimensionnement évident de la Région Bucarest-Ilfov (1,821 km$^2$) par rapport a d’autres régions, comme par exemple la Région Métropolitaine de Budapest (8,930 km$^2$) ou la Zone Métropolitaine de Prague (3,913 km$^2$), se situant, compte tenu des dimensions réelles, entre les agglomerations urbaines de Budapest (2,536 km$^2$) et de Prague (1,667 km$^2$); b) un évident sous-dimensionnement du territoire du Municipe de Bucarest, qui a une densité d’habitants au moins double comparativement a d’autres capitales (Bucarest--8,893 habitants/km$^2$, par rapport a Prague, Varsovie et Budapest--2,418, 3,284 et, respectivement, 3,554 habitants/km$^2$), ce qui explique l’extension de certaines fonctions au territoire des communes environnantes et la nécessité future d’un développement corrélé a celui des communes de l’agglomeration urbaine. On présente, également, le cadre général de développement économico-social du Municipe de Bucarest, l’histoire du développement de la localité, sa position géographique ayant des influences directes sur l’évolution et la tendance économico-sociale dans la période 1990--2006. Dans un travail prochain, on présentera des aspects relatifs a la place de la Capitale dans l’économie du pays, son potentiel économique et certains éléments concernant la qualité de la vie et le comportement des habitants de la Roumanie.
L’article ci-présent représente la suite de l’article paru dans le numéro antérieur de la revue et présente des aspects concernant les conditions que Bucarest doit remplir pour qu’a l’horizon de l’an 2025 il puisse acquérir le statut de métropole européenne, ayant un rôle spécifique régional, continental et intercontinental. L’économie du Municipe de Bucarest sera prioritairement axée sur des activités de services, sphere qui concentrera une grande partie de la population occupée et ou l’on réalisera quelque 85% du total du Produit Intérieur Brut de la Capitale, a l’horizon de l’an 2025. La qualité de la vie, évalue compte tenu du degré de développement des activités et des services directement visant assurer une vie décente a la population (degré exprime par des indicateurs économico - financieres), ainsi que par les appréciations faites par la communauté, connaitra des améliorations considérables. Pour que le Municipe de Bucarest puisse parcourir toute la trajectoire qui lui assure la possibilité de devenir, d’une Capitale d’envergure européenne, une Capitale européenne d’envergure, ayant les traits caractéristiques d’une authentique métropole du troisieme millenium, il faudra remplir les conditions sine-qua-non suivantes: réaliser des mutations profondes de l’état économique de la Capitale et de sa population; moderniser progressivement le profil économique de Bucarest, pour obtenir des décalages importants dans le positionnement du secteur tertiaire et des industries faisant appel aux nouvelles technologies; structurer, afin de renouveler, le domaine de l’équipement commercial et a services, tout en établissant de nouveaux équilibres entre le commerce de grandes surfaces et le commerce de proximité, a divers degrés de spécialisation; amener, a un standard européen de qualité, les rues des zones extra centrales (pavage, réseau d’eau et canalisation, gas); revigorer certains services traditionnels pour la population de Bucarest: services de réparations, confectionnement sur commande, entretien du patrimoine immobilier; approfondir les facteurs de qualité de la vie, des relations interhumaines et du développement de la culture; repenser la trame des rues, créant de nouvelles axes de circulation majeure, y compris un systeme annulaire de transport, connecte aux corridors européens de transport IV (Vienne – Budapest – Bucarest) et VII (Liov – Bucarest – Giurgiu); créer un systeme d’arteres routieres et de transport public avance (passages dénivelés, moyens modernes de transport); réhabiliter le Centre historique et rénover les bâtiments anciens; organiser des activités d’ampleur européenne, constituer un puissant centre commercial et d’affaires dans cette partie de l’ Europe; finaliser les aménagements sur les rivieres Arges et Dambovita: raccorder Bucarest, apres 2015, a la principale artere transeuropéenne de navigation Rhin-Main-Danube.
The improvement of causeway’s bitumen adhesiveness is becoming a current practice in our country, especially when is used acid (siliceous) aggregate. One of the most important properties of bitumen is its adhesiveness to aggregate, and this property determine the using of bitumen in causeways area. Usually the adhesiveness is defined as the capacity of a binder to cover an aggregate without dispersing itself when touching the water or the traffic aggressions. Therefore, the adhesiveness additives are products that improve the adhesiveness of the bitumen to a certain aggregate. The used additives – ADETEN type (A01 and A03) have a high stocking stability, a low toxicity degree toward the amine, diamine, polyamine-based additives and are liquid products perfectly compatible with all bitumens and easy to use, in comparison to the paste or solid additives, which must be made liquid to be used. But a very important condition, which must be fulfilled by these promoters is the heat-resisting condition.
The results of laboratory tests for two additives: ADIROL ALCAMID F and ADIROL ALCAMID FS are presented. Three mixtures were made in laboratory, with two types of bitumen of four dosages each, in order to assess characteristic physical and mechanical values of mixtures made with bitumen having 0.5% additives. The analysis of obtained results shows a substantial improvement of the characteristic physical and mechanical values of these mixtures as compared to mixtures made with non-additive bitumen.
For determining the adherence stresses concrete-to-concrete a device for wrestling of added layer to the support is used, according to the Romanian norms. The connection to the determination apparatus is realized by a metallic plate bonded with special adhesive. The value of this stress is in many cases bigger than the adhesive strength, therefore the metallic plate detaches oneself before the separation of the added concrete.
Mechanical joining techniques are used in construction industry all over the world on a daily basis. A further method of joining has proven to be highly successful – adhesive bonding. Known for thousands of years, adhesive bonding has become as important as other joining techniques as a result of the pace of developments in recent years. In many areas, this bonding technology has become a key technology. Virtually, all solid materials can be connected with one another using adhesives. Although bonding fibre reinforced polymeric composites to the concrete substrate is a relatively simple technique, the proper installation of the fibre reinforced polymeric composites is essential to ensure the adequate performance of the hybrid system. Since the installation procedures differ from one system to another, appropriate specifications will be clearly presented. The paper will include requirements to provide a quality joint assembly, meaning the special pre-treatments of the concrete surface. The material to be bonded is cleaned and prepared so that adhesives can adhere better to them.
The estimation of the capacity of coverage in the laboratory may be made visually as well. The operator ’s subjective perspective, the angle of view, the luminosity, the nature and colour of aggregates are many factors that may influence the result. The computer-assisted image analysis qualifies and quantifies objectively enough the capacity of coverage of bitumen on aggregates, removing any exterior influences. It is a simple, repeatable and reproducible used method.
In recent decades, tremendous success has been achieved in the advancement of chemical admixtures for Portland cement concrete. Most efforts have centered on improving the properties of concrete with minimal investments by ready-mix suppliers and contractors in the way of specialized equipment or special skills and education of their labor forces. This approach has resulted in construction cost reductions and universally accepted ready-made remedies for unexpected problems during construction. The behavior of concrete improved with superplasticizers additives is studied.
Whether built in the 17th or in the 20th centuries, adobe buildings share common problems of maintenance and deterioration. These types of buildings represent today in Romania a traditional house for country people. It also makes recommendations for preserving adobe buildings. By its composition, adobe construction is inclined to deteriorate; however, the buildings can be made durable and renewable when properly maintained.
