Evaluation of pounding effects between reinforced concrete frames subjected to far-field earthquakes in terms of damage index

In this paper, three different damage indexes were used to detect nonlinear damages in two adjacent Reinforced Concrete (RC) structures considering pounding effects. 2-, 4- and 8-story benchmark RC Moment Resisting Frames (MRFs) were selected for this purpose with 60%, 75%, and 100% of minimum separation distance and also without any in-between separation gap. These structures were analyzed using the incremental dynamic analysis method under 44 far-field ground motion records. Comparison of the results between the MRFs with and without considering pounding effects show that collisions lead to a decrease in the values of coefficient of determination and the nonlinear damage occurs in lower seismic intensity. As a result, using the damage indexes, nonlinear damages can be detected during a specific seismic intensity. Moreover, considering a minimum separation distance leads to an increase in the coefficient of determination between the damage index and the maximum story drift ratio. Furthermore, due to pounding, shorter MRFs are damaged more significantly than the taller structures.

The analysis of aircraft equipment essential for the use of ADS-B, implementation in 2021

The fluidity of air traffic depends mainly on the coherence of the minimum separation requirements between aircraft in the airspace and the advanced exchange of air traffic information obtained through the interoperability of ATM systems and surveillance data exchange systems between aircraft and ATM system. In the paper on the implementation of unified global solutions, ICAO indicated that the key requirement is that the functions of on-ground ATM systems concerning the source of information surveillance (aircraft position). ICAO encourages the widespread use of ADS-B technology (Automatic Dependent Surveillance – Broadcast). The paper presents the concept of using ADS-B, analyzes the problems resulting from the need to ensure interoperability, and shows the results of measurements and analyzes of the actual equipment level of aircraft operating from two airports in TMA Warsaw: Warsaw Chopin Airport (EPWA) and Warsaw Modlin (EPMO). In summary, the authors refer to the level of meeting the requirements of the ADS-B equipment in the context of formal and legal requirements and the time remaining until the published requirements are fully applicable.

Effect of passive coupling on seismic interaction optimization of adjacent structures

During the past few years, several studies have been conducted in various fields of civil engineering in order to design structures that can withstand the forces and deformations that might occur during seismic events. However, more recently, building adjacent structures close to each other and more resistant to earthquakes, provided with coupling systems, has been an issue of major concern. The effects of some parameters, such as the characteristics of adjacent structures and those of the coupling system, on the choice of the separation distance, were investigated using a program that was developed using MATLAB. This article aims to present a study that is intended to determine the parameters characterizing the coupling system. Moreover, the influence of rigidity of the structure was also examined. For this, three examples were investigated: a flexible structure, a rigid structure, and a very rigid structure. The results obtained from the numerical study made it possible to show that knowing the characteristics, number, and arrangements of the coupling systems can be used to find the minimum separation distance between two adjacent buildings.

Optimization of the Distance between Two Adjacent Multi-Story Buildings by Calculating the Earthquake Effect in Yogyakarta

Neo Malioboro and Malioboro Suite Hotels are two adjacent multi-story buildings in Yogyakarta with a fairly close distance of 2.5m (Lx) between their structures. Considering that Yogyakarta is an area prone to earthquakes, the relatively close distance between the two hotels has triggered research interest. The research was carried out by taking hotel planning data in the form of structural and architectural drawings modeled in SAP2000.14 to obtain structural behavior toward existing designs such as natural shear periods, base shear, mass participation, and to obtain deviation values between floors (drift ratio) and the center of mass deflection (δ). The largest deviation value of the two hotels in the joint reviewed occurred on the top floor, with the maximum deviation value of 0.440m (δM1) for Neo Malioboro and 0.412m (δM2) for Malioboro Suite. The minimum deflection distance between the two hotels was 0.602m (δMT), resulting in the minimum separation distance for the two hotels of 1.454m. The results revealed that the distance of the two hotels was in a safe condition because it was greater than the required minimum separation distance of 2.5m > 1.454m.

Foam Formation by Compression/Decompression Cycle of Soft Porous Media

A theory of the amount of foam produced by compression/decompression cycles of a soft porous media is developed. The amount of foam produced was found to be dependent on both the amount of surfactant within the media and the minimum separation between the plates of the compression device. The latter is determined by the mechanical properties of the soft media. The theory also shows the importance of the decompression of the media as this is the mechanism of where the air penetrates into the soft porous material. The accumulated air is used during the compression stage for foam formation. The theoretically predicted values of foam mass are found to have good agreement with experimental observations, which validates the theory predictions. The theory also predicts independence of the foam produced in terms of the frequency of compression/decompression cycles, which agrees with our experimental observations.

Tying Devices to Mitigate Pounding of Adjacent Building Blocks

Adjacent building blocks separated by thermal expansion joints are vulnerable to pounding during earthquakes. The specified Saudi building code minimum separation may be very large and does not necessarily eliminate pounding forces. This research discusses the feasibility of tying the adjacent building blocks with simple devices to mitigate structural pounding when separated by thermal joints. Six and twelve-story moment resistance frames of intermediate ductility were designed for seismic loads of moderate risk. The seismic response was studied for frames with variable separation distances in three cases related to thermal joint, code minimum separation, required separation to eliminate pounding force, and in a fourth case in which the tying device was used along with thermal separation. A linear elastic model was used to model the assigned gap links between the adjacent building blocks. The tying device was modeled with a tension-only hook element. Four normalized earthquake records were used with inelastic-time history analysis to assess the seismic response of the adjacent building blocks. The proposed tying devices reduced successfully the pounding forces by 40% to 60% for adjacent building blocks with installed thermal separations. Building damage as observed from damage index and the hysteretic response was not influenced by the pounding force, indicating that the tying may be used on existing buildings with thermal separation as a partial mitigation technique to reduce the pounding hazard in such cases. Further improvement on the tying device will increase the mitigation of the pounding hazard.