Study on the New Method of Constructing Shear Walls in Multi-Storey Buildings With Site Cast Reinforced Concrete Frame System

The article touches upon the comparative analysis of bearing system calculations of a multi-storey residential building with site cast reinforced concrete frame and shear wall constructed by two different methods. In the calculation models, the shear walls are constructed from site cast reinforced concrete in the first case, and from three-layer sound and thermal insulating bearing panels in the second. The calculations have been made considering the impact of the seismic force. According to the calculation results, the dynamic parameters of the bearing systems of the buildings and the economic efficiency indicators have been compared. Considering the fact that in the recent years three-layer sound and thermal insulating panels have been widely used in the world, the study attempted to reveal the efficiency of using such panels in the Republic of Armenia.

DEGRADATION DAMAGE OF REINFORCED CONCRETE FRAME IN LONG-TERM EXPLOITATION

A method for calculating a reinforced concrete frame under rheological deformation conditions is proposed, taking into account degradation damage as a result of corrosion during long-term operation, reflecting their real work under the combined action of a load and an aggressive environment based on the modern phenomenological theory of deformation of an elastic-creeping body. The possibility of considering the processes of long-term deformation of reinforced concrete in conditions of long-term exploitation is shown. Analytical dependencies and a calculated example are given for the considered service life.

Simplified Pushover Analysis for Rapid Assessment of Shear-Type Frames

A simplified pushover method for rapidly assessing the seismic capacity of shear-type frames is presented. The frame global force-displacement capacity is described as a trilinear curve passing through three limit states (LS): Damage LS (DLS), Life safety LS (LLS), and Collapse LS (CLS). The global LSs are obtained consequently to the attainment of story-level, element-level, and section-level LSs. All LS capacities are described through closed-form equations. The validity of the proposed method is verified by applying it on several reinforced concrete (RC) frames with a varying number of stories. The results obtained with such an analytical procedure show a good match with those obtained from pushover based on finite element method (FEM) analysis models, in terms of both global force-displacement capacity curves and story displacements at various LSs. The proposed method has the potential to be conveniently applied in large-scale vulnerability/risk assessment studies, where the quality and quantity of the available data call for the use of simplified yet accurate models. More refined models would in fact require significantly heavier computational efforts, not justified by the quality of the results that are usually obtained. The simplicity of the proposed method in such a context is demonstrated through the development of the fragility curves of a five-story shear-type reinforced concrete frame, starting from a predefined set of mechanical and geometrical features characterizing a building typology.

The effect of vertical near-field ground motions on the collapse risk of high-rise reinforced concrete frame-core wall structures

According to the observations of past earthquakes, the vertical ground motions have had a striking influence on the engineering structures, especially reinforced concrete ones. Nevertheless, the number of studies on their aftermath is insufficient, and despite some endeavors done by researchers, there is still a shortage of knowledge about the inclusion of vertical excitation on the seismic performance and the collapse probability of RC buildings. Hence, the variation in the collapse risk of three high-rise RC frame-core wall structures when they undergo bi-directional ground motions is discussed. In this paper, incremental dynamic analyses are carried out under two circumstances, including the horizontal (H) and the combined horizontal and vertical (H+V) earthquakes, and the seismic fragility curves are derived. The inter-story drift ratio corresponding to the onset of collapse has also been defined. The buildings collapse risk under the two circumstances is obtained from the risk integral. Results indicate that in the H+V state, structures meet the collapse criteria for lower intensity measures. Thus, the collapse risk increases as the structures are subjected to bi-directional seismic loads, and the consideration of this effect leads to a more accurate evaluation of buildings seismic performance.