Experimental analysis of strengthening solutions for the out-of-plane collapse of masonry infills in RC structures through textile reinforced mortars (original) (raw)
Related papers
Proceedings of the 7th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering (COMPDYN 2015), 2019
Past and more recent seismic events worldwide clearly showed that a crucial issue for lifesafety and loss reduction due to earthquakes for existing reinforced concrete (RC) buildings is related to the out-of-plane (OOP) collapse of infill masonry walls. In literature, few studies addressed this paramount topic, above all about the proposal of strengthening strategies to prevent the infills' collapse. This paper presents an experimental work about the assessment of possible strengthening solutions designed to mitigate or prevent the out-of-plane collapse of masonry infills in existing RC buildings. Three nominally identical full-scale one-bay-one-story RC frames were built and infilled with a thin masonry wall made up of horizontal hollow clay bricks. The first specimen was representative of the enclosure of a typical existing RC building in the Mediterranean region in its "as-built" condition. The remaining two specimens were strengthened against the out-of-plane collapse by means of two different strengthening techniques based on the application of innovative systems made up of high-ductility mortar plaster and fibre-reinforced polymer nets. All the tests consisted in the application of a semi-cyclic (loading-unloading-reloading) history of imposed displacements in the OOP direction by means of small pneumatic jacks through a uniform distributed load. Experimental results are shown in terms of OOP force-displacement responses, deformed shapes and damage evolution. In the end, the results of the tests are compared to assess the effectiveness of the selected strengthening techniques and to provide a support towards the choice of the best strategies for future further investigations and applications.
A Simple Strengthening Method for Preventing Collapsed of Vulnerable Masonry Infills
Buildings
A series of structural tests were conducted to examine the seismic performance of masonry infills strengthened with particular materials on infilled reinforced concrete (RC) frame structures. Six 1:4 scaled-down RC frame specimens had been prepared, including one brick-infilled frame without strengthening and five brick infills strengthened with innovative strengthening materials. The materials were steel wire mesh, chicken hexagonal wire mesh, plastic wire mesh, fiber-reinforced polymer (FRP), and plastic stretch film. The strengthening was diagonally applied on both surfaces of the masonry infill. The steel wire mesh, chicken hexagonal wire mesh, and plastic wire mesh were sewn using steel wire, while the FRP sheet was glued using epoxy resin and the plastic stretch film was glued using synthetic rubber adhesive. The specimens were tested following the FEMA 461 standard testing protocol, which involved applying lateral static cyclic loading to the specimens. The displacement trans...
Seismic Strengthening of Masonry Infilled Reinforced Concrete Frames
Structural frames are often filled with masonry panels for architectural purposes as divisional walls or cladding. There has been much work conducted into the seismic behaviour of infilled frame buildings (e.g., Abrams, 1994–1996; Chrysostomou et al, 1992; Žarnić and Tomažević, 1984). However, the most significant outcome is perhaps the general consensus that brickwork infill can have a beneficial effect on the overall seismic performance of the building if it is properly tied into the rest of the building. The purpose of the present study was to investigate possible seismic strengthening options for use in the seismic upgrade of a infilled frame structures with an emphasis on strengthening brick masonry infill walls. In order to test the numerical models and to define a simple method for analysing the behaviour of reinforced concrete frames with infill in earthquake regions, we have done a series of tests with the aim to investigate the behaviour of strengthened infills of RC frame...
Experimental work on seismic behavior of various types of masonry infilled RC frames
Structural Engineering & Mechanics
Reinforced concrete frame structures with masonry infill walls constitute the significant portion of the building stock in Turkey. Therefore it is very important to understand the behavior of masonry infill frame structures under earthquake loads. This study presents an experimental work performed on reinforced concrete (RC) frames with different types of masonry infills, namely standard and locked bricks. Earthquake effects are induced on the RC frames by quasi-static tests. Results obtained from different frames are compared with each other through various stiffness, strength, and energy related parameters. It is shown that locked bricks may prove useful in decreasing the problems related to horizontal and vertical irregularities defined in building codes. Moreover tests show that locked brick infills maintain their integrity up to very high drift levels, showing that they may have a potential in reducing injuries and fatalities related to falling hazards during severe ground shak...
IRJET, 2022
Buildings are subjected to a variety of natural hazards over their mean lives and around the globe structural multi-hazard analysis and design has become a hotbed of research. Earthquake and progressive collapse seem to be two of the major threats for these constructions. Consequently, limited research on the effects of seismic and progressive collapse designs on multi-story buildings has been done. A building's construction also contains a variety of structural and non-structural parts for various functions. When examining structural members, we as structural engineers, tend to focus on the structural members for resistance of buildings against any hazard and Non-structural components are often overlooked. However, several studies have shown that non-structural parts, such as infill walls, play a key role in increasing building resistance to natural disasters. As a result, the role of the infill wall against various risks must be investigated. The effect of infill walls in the case of progressive and seismic collapse of RC structures has received far less attention. In this study, it is decided to evaluate effect of different infill wall configuration in case of combine study of seismic and progressive collapse of reinforced concrete structures by using ETABS software. For this purpose four models 1) Bare Frame 2) Fully In-filled Frame 3) Open Ground Frame and 4) Open Ground & Intermediate Frame have been considered.
Reinforced Concrete Frames with Masonry Infills. Damages and Consolidation Measures
This paper presents a synthesis of the typical damages recorded in reinforced concrete frames and masonry infills after recent earthquakes. The behavior and failure modes of the infill walls are of great importance, especially since no clear recommendations are provided in the current design codes for the performance of these types of walls. In the present time, masonry infill walls are considered to be non-structural building elements, while the seismic behavior of reinforced concrete frame structures having these type of walls, indicated a structural behavior of the infills. Several proposals for the improvement of the out-of-plane behavior of infill walls are presented in this paper. The investigation of these solutions can lead to the development of innovative systems of masonry infills, and can also provide viable consolidation measures for existing buildings.
Seismic Performance of Reinforced Concrete Buildings with Masonry Infill
Unreinforced masonry Infills modify the behavior of framed structures under lateral loads; however, in practice, the infill stiffness is commonly ignored in frame analysis, resulting in an underestimation of stiffness and natural frequency. The structural effect of hollow concrete block infill is generally not considered in the design of columns as well as other structural components of RC frame structures. The hollow concrete block walls have significant in-plane stiffness contributing to the stiffness of the frame against lateral load. The scope of present work was to study seismic performance of reinforced concrete buildings with masonry infill in medium rise building. The office medium rise building is analyzed for earthquake force by considering three type of structural system. i.e. Bare Frame system, partially-infilled and fully-Infilled frame system. Effectiveness of masonry wall has been studied with the help of five different models. Infills were modeled using the equivalent strut approach. Nonlinear static analyses for lateral loads were performed by using standard package ETABS, 2015 software. The comparison of these models for different earthquake response parameters like base shear vs roof displacement, Story displacement, Story shear and member forces are carried out. It is observed that the seismic demand in the bare frame is significantly large when infill stiffness is not considered, with larger displacements. This effect, however, is not found to be significant in the infilled frame systems. The results are described in detail in this paper.
The in plane behavior of masonry infill walls that are subjected to lateral loading simulating the effects of earthquakes on buildings has been the subject of many studies. The present work is focused on a problem that has been hardly studied and refers to the vertical action on such walls. In particular, it concerns a vertical action that evolves when a supporting column of a multi-story reinforced concrete frame with infill masonry walls fails. Such failure may happen as a result of extreme loadings for instance a strong earthquake, car impact, or military or terror action in proximity to the column. Without infill walls, the loss of a supporting column may lead to a partial or even full progressive collapse of the bare reinforced concrete frames. The presence of masonry infill walls may restrain the process and even prevent the development of a progressive collapse mechanism. The aim of this study is to look into the role of the composite action of a frame and an infill wall in the event of loss of a supporting column. The study adopts an experimental methodology and numerical methods aiming to evaluate the contributions of the unreinforced masonry infill, to examine its interaction with the frame, and to quantify its contribution to the resistance of the bare frame under such circumstances.
Infill masonry: seismic behavior of reinforced solutions
2011
The analysis of buildings constructed in the last 20 years, designed following modern standards, may lead to worrying conclusions. Images of out-of-plane expulsions and in-plane failures of infill walls in recent seismic activities around the world reminded engineers of the consequences of bad practice, wrong solutions or inadequate design. With the above in mind, a research program is being conducted as a partnership between University of Minho and the National Laboratory for Civil Engineering (LNEC), which includes a shaking table experimental program of framed concrete buildings with masonry infill walls, reinforced and unreinforced. Herein the shaking table program and the tested solutions are detailed, along with the discussion of the results, focusing on the local behaviour of the infills and the global behaviour of the concrete structure.
Seismic Vulnerability of Masonry Infilled Reinforced Concrete Frames
This study assesses the seismic vulnerability of ductile reinforced concrete frames with masonry infill walls, utilizing nonlinear dynamic analysis of building models. The evaluation is based on structures designed and detailed according to Eurocodes. The research quantifies the effect of presence and configuration of masonry infill walls on the seismic collapse risk using Incremental Dynamic Analysis within the performance-based framework. Seismic vulnerability assessment indicated that of the configurations considered (bare, partially-infilled and fully-infilled frames), the fully-infilled frame had the lowest collapse risk and the bare frame is found to be the most vulnerable to earthquake-induced collapse.