Technical regulation and development of design codes
Response spectra (maximum response spectra) for earthquakes, but not dynamism coefficients for setting seismic effects
Authors: Kurbatsky E.N., Mazur G.E., Mondrus V.L.
Key words: seismic effects, dynamic coefficients, response spectra, foreign standards, Russian codes
In the magazines № 1 of ACADEMIA and in № 3 of Natural and technogenic risks. Building Safety in 2019, was published an article about dynamic coefficients or spectra of reactions (responses) of structures to seismic effects. In these articles it was noted that the outdated concept of «dynamic coefficient» continues to be used in the Russian Federation Code. These articles answer the question presented in the heading of the above-mentioned articles.
But in none of the of the Russian Federation seismic Code (SP 14.13330.2018, SP 268.1325800.2016, etc.) there is no definition of this concept. The authors of the project of Code 14.13330.2019 tried to fill this gap and to determine the dynamic coefficient through static displacement during an earthquake.
We believe that such a definition does not have physical meaning. For a seismic impact it is impossible to correctly determine the static impact which must be multiplied by the dynamic coefficient. It does not define anything and, most likely, is entered into the text only for the sake of formal filling of the corresponding section. The presence of such meaningless concept in normative documents impedes normal work on improving the regulatory framework and can not only divert one from understanding the phenomenon, but also lead to incorrect decisions. We propose to exclude «dynamic coefficients» from the Russian codes relating to seismic effects and replace them with response spectra. The rationale
for this proposal will be devoted to this article.
The concept of response spectra is recognized throughout the world, including Russia. It is known that the number of countries where this concept is used in the national codes is more than fifty.
After the publication of the article «Dynamic coefficients or spectra of reactions (responses) of structures to seismic effects?» we received many reviews, both from designers and from well-known scientists who were affected by the topic that we raised. Therefore, we consider it necessary to continue its discussion.
Actualization of existing guidelines taking into account a new seismic scale
Authors: Uzdin A.M., Nikonova N.V., Nazarova Sh.Sh., Sabirova O.B.
Key words: peak acceleration, seismic intensity scale, design standards, the period of oscillation
The possibility of coordination of the existing Guidelines «Construction in Seismic Areas» and GOST «Earthquakes. Seismic Intensity Scale», which operates with different values of peak ground accelerations, is considered. It is proposed, keeping maps A, B and C as a basic indicator of the earthquake frequency, to calculate seismic intensity using formulas available in the seismic scale. Then the value of seismic intensity will be fractional, and formulas for calculating the intensity value and peak accelerations are available in GOST, i. e. they are legalized. In addition, it is necessary to eliminate the reserves inherent in the Guidelines by clarifying the combination coefficients, introducing modal amendments for damping, and taking into account the spatial work of structures. For particularly dangerous areas, to which the modern Guidelines does not apply, the use of modern technical solutions is proposed: seismic isolation, seismic damping, structures with design scenarios for damage accumulation.
Seismic engineering passport of the building – a basic document on the technical condition and safety of the housing stock
Authors: Berzhinsky Yu.A., Berzhinskaya L.P., Ivankina L.I., Salandaeva O.I.
Key words: unified information system, certification of buildings, data banks, seismic engineering passport, reference network of representative buildings, earthquake resistance class of buildings.
As part of the R&D unit of the Federal Target Program for Seismic Safety of the Russian Federation in 2011‑2013, the concept of the Unified Information System of the EIS «Seismic Safety of the Territory of Russia» was developed and its individual elements were implemented. When forming the databanks, questions arose regarding the unification of engineering seismic certificates of buildings, the main form of presenting information about their seismic resistance. The use of the ISS passport form in accordance with GOST 31937‑2011 was insufficient to reflect the collected information about the earthquake resistance of buildings. On the example of a survey of the housing stock of the city of Shelekhov, Irkutsk
Region, the optimal structure of the ISS passport was worked out in practice.
Fire behavior of translucent facades of residential high-rise buildings
Authors: Kaziev M.M., Bezborodov V.I.
Key words: high-rise residential buildings, fire safety, translucent structures, facade structures, progressive spread of fire, full-scale fire tests, fire resistance of translucent structures, temperature fields, fire-prevention inter-floor belt, height of the flame
One of the indicators of fire safety of buildings is the ability of translucent facades to resist destruction and thus prevent the transition of fire to the overlying floors. Analysis of real fires in high-rise buildings has shown that when the flame goes out, the fire can get a progressive spread throughout the facade of the building. To assess the risk of fire spreading along the facade and substantiate the necessary and sufficient fire safety requirements, it is necessary to know the dynamics and the maximum possible level of thermal impact of a real fire, which may be exposed to the translucent structure of the overlying floor. This will allow us to assess the actual fire resistance of the translucent structure in the conditions of thermal impact in a real fire and to justify the necessary and sufficient ability of the translucent structure
to resist destruction. Solving this issue will also allow us to develop effective ways and design solutions to prevent the spread of fire on the facades of high-rise buildings. The article presents the main provisions of the methodology and the results of a full-scale fire experiment to study the behavior of the translucent facade of high-rise residential buildings in a real fire. In particular, the experiment allowed us to establish the distribution of temperature fields on the facade of the building above the floor of the fire at the maximum stage of its development.
Design analysis, design of components, buildings and structures
Once again on setting the design seismic input
Authors: Uzdin A. M., Nazarov S. S., Prokopovich S. V., Rumyantsev D. A.
Key words: design seismic input, limit state, acceleration amplitude, peak acceleration
The paper raises the question of requirements for design seismic input. First of all, it is noted that the design input must be more dangerous for a construction than the actual one; the input hazard must be assessed basing on the structure possible limit state and the design input should not lead to excessive costs. In this case, the external similarity of model and real actions is not required at all. Seismic input indicators, which should be taken into account when generating model inputs, are considered. It is noted that for the one and the same structure, several design inputs corresponding to the accepted limit states should be used. Rigid normalization of the design acceleration amplitude in the framework of the Guideliness is completely unacceptable.
