scholarly journals Evaluation of timber floor in-plane retrofitting interventions on the seismic response of masonry structures by DEM analysis: a case study

2021 ◽  
Author(s):  
Alessandra Gubana ◽  
Massimo Melotto
Keyword(s):  
Seismic Response ◽  
Masonry Wall ◽  
Masonry Building ◽  
Masonry Structures ◽  
Seismic Behaviour ◽  
Cyclic Behaviour ◽  
Out Of Plane ◽  
Dem Analysis ◽  
Side Walls ◽  
Seismic Forces

Abstract The seismic response of existing masonry structures is strongly influenced by floor and roof in-plane properties. An in-plane strengthening intervention is often needed on traditional timber floors to overcome their low in-plane stiffness and to preserve historical buildings. In this study, the effect of un-stiffened and stiffened timber floors on the seismic behaviour of an existing listed masonry building is investigated with dynamic non-linear analyses by means of the Discrete Element Method (DEM). With this approach, the failure processes and collapse sequences of masonry structures can be followed in detail. A previously developed model of the floor cyclic behaviour, based on experimental data, is here applied in the DEM models of the masonry building. Different seismic ground accelerations, different floor types and different wall-to-diaphragm connections are considered. The results highlight the effectiveness of the analysed floor strengthening solution in reducing the out-of-plane displacements of masonry walls. With adequate connections, the reinforced floor is able to transfer the seismic forces to the shear resistant walls up to the shear-sliding collapse of the side walls of the structure. A comparison with the ideal rigid diaphragm case confirms the good performance of the strengthened floors. The small observed out-of-plane displacements are compatible with the masonry wall capacity, and the reinforced floor hysteretic cycles contribute to dissipating part of the input energy. Moreover, different designs of the connections can also cap the transferred seismic forces to an acceptable level for seismic resistant walls.

scholarly journals Evaluation of timber floor in-plane retrofitting interventions on the seismic response of masonry structures by DEM analysis: a case study

2021 ◽  
Author(s):  
Alessandra Gubana ◽  
Massimo Melotto
Keyword(s):  
Seismic Response ◽  
Masonry Wall ◽  
Masonry Building ◽  
Masonry Structures ◽  
Seismic Behaviour ◽  
Cyclic Behaviour ◽  
Out Of Plane ◽  
Dem Analysis ◽  
Seismic Forces

AbstractThe seismic response of existing masonry structures is strongly influenced by floor and roof in-plane properties. A strengthening intervention is often needed for traditional timber floors to overcome their low in-plane stiffness and to preserve historical buildings. In this study, the effects of unreinforced and reinforced timber floors on the seismic behaviour of an existing listed masonry building are investigated with dynamic non-linear analyses by means of the Discrete Element Method (DEM). With this approach, the failure processes and collapse sequences of masonry structures can be captured in detail. A previously developed model of the floor cyclic behaviour, based on experimental data, is applied herein to DEM models of the masonry building. Different seismic ground accelerations, different floor types and different floor-to-wall connections are considered. The results highlight the effectiveness of the analysed floor strengthening solution in reducing the out-of-plane displacements of masonry walls. With adequate connections, the reinforced floor is able to transfer the seismic forces to the shear-resistant walls up to the shear-sliding collapse of the structural sidewalls. A comparison with the ideal rigid diaphragm case confirms the good performance of the strengthened floors. The small observed out-of-plane displacements are compatible with the masonry wall capacity, and the reinforced floor hysteretic cycles contribute to dissipate part of the input energy. Moreover, different designs of the connections can also cap the transferred seismic forces to an acceptable level for shear-resistant walls.

Seismic Behaviour of Rocking Elements Reinforced with Composite Materials

2017 ◽  
Vol 747 ◽  
pp. 604-611
Author(s):  
Simona Coccia ◽  
Fabio di Carlo ◽  
Stefania Imperatore
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Dynamic Equation ◽  
Masonry Wall ◽  
Rigid Bodies ◽  
Masonry Structures ◽  
Seismic Behaviour ◽  
Gfrp Bars ◽  
Out Of Plane ◽  
Vertical Walls

Seismic behaviour and vulnerability of existing masonry structures are typically characterized by out-of-plane response of vertical walls. The dynamic response of such elements can be analytically assessed considering the dynamic equation of rigid bodies not resistant to tensile stresses. Many studies available in literature have highlighted the vulnerability of this type of structures against out-of-plane movements. In order to withstand horizontal seismic actions, appropriate and effective retrofitting interventions have to be properly designed. In this paper, the rocking response of a masonry wall retrofitted with elastic GFRP bars is investigated. A parametric survey is also carried out, to evaluate the increase in strength of the masonry wall, due to the presence of the composite material.

scholarly journals A Review on Effect of Pile Stiffness on Seismic Response of Structure

2021 ◽  
Vol 9 (12) ◽  
pp. 772-774
Author(s):  
Mohit Bharat Dange
Keyword(s):  
Seismic Response ◽  
Pile Foundation ◽  
Seismic Loading ◽  
Pile Foundations ◽  
Seismic Behaviour ◽  
Foundation Design ◽  
Earthquake Loads ◽  
Pile Cap ◽  
Seismic Forces ◽  
Shaky Ground

Abstract: Pile foundations are widely employed for a variety of structures on shaky ground. The importance of seismic design in ensuring the effective operation of a structure under severe seismic loading conditions cannot be overstated. For the analysis of seismic forces on a structure, IS 1893 will be employed. This research entails the choosing of a specific form of building structure. A comparison of buildings with and without pile foundations will be shown. Because of the differences in their properties, the seismic behaviour of the various structures differs. The influence of pile stiffness on the structure's seismic response will be investigated. The rigidity of the piling foundation could have an impact on the structure.With the rise in seismic activity, there may be a need for more efficient pile foundation design to withstand earthquake loads. The major goal of this study is to compare pile stiffness with changes in diameter and zone. Keywords: Pile Foundation, STAAD-Pro, Structure, Stiffness, zone, Pile Cap, Load Estimation, Pile cap, Pattern of Pile.

scholarly journals Statics and Kinematics in Cyclic Behaviour of Semi-Rigid Steel Structures

2016 ◽  
Vol 6 (2) ◽  
pp. 25-32
Author(s):  
Corina - Ana Moldovan
Keyword(s):  
Constitutive Relation ◽  
Steel Structures ◽  
Numerical Results ◽  
The Other ◽  
Base Shear ◽  
Seismic Behaviour ◽  
End Plate ◽  
Cyclic Behaviour ◽  
Lateral Displacements ◽  
Seismic Forces

Abstract The contribution presents a set of seismic analyses of multi - storey steel structures with semi-rigid beam column connections acted upon by seismic actions. Semi-rigidity of the structures beam to column connections is conferred by two types of beam to column connections: top and seat and web angle (TSW) and end-plate (EP) joints. Computed numerical results are associated to two classes (static and kinematic) of seismic behaviour parameters expressing the two contradictory effects of semi-rigidity. On one hand, the lateral flexibility induces larger lateral displacements while, on the other hand, it attracts smaller base shear seismic forces. Also, the constitutive relation M − θr induced into semi- rigid beam column connections by seismic actions is presented. The results are presented in their numerical form and in a comparative graphical manner allowing for relevant comments and conclusions

scholarly journals Out-of-Plane Shaking Table Tests on Seismic Response of RC Frame Infilled with a New Type of Shale Fired Heat-Insulation Blocks

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jian Wu ◽  
Li-dan Zhang ◽  
Qing Yu ◽  
Bo Wang
Keyword(s):  
Seismic Response ◽  
Heat Insulation ◽  
Masonry Wall ◽  
Shaking Table ◽  
Rc Frame ◽  
Out Of Plane ◽  
Rigid Connection ◽  
New Type ◽  
Infill Masonry ◽  
Insulation Block

Shale fired heat-insulation block, which is made of shale, fly ash, building rubbish, and waste paper, is a new type environment-friendly product. In order to study the mechanical properties of shale fired heat-insulation block walls, four full-scale walls were tested under El-Centro, Taft, and Ninghe earthquakes using shaking table equipment, in which the influence of the spacing of cast-in-place belt and the connection between the wall and the frame on the out-of-plane seismic performance of the wall was taken into account. The subject of this study is mainly about out-of-plane dynamic response of masonry walls in terms of frequency, displacement, and acceleration. It could be concluded that the cast-in-place belt and the rigid connection between wall and RC frame could effectively reduce the out-of-plane seismic response of the infill masonry wall. Finally, the recommendations for the use of this type of block in the structure are given.

scholarly journals Masonry Walls Retrofitted with Vertical FRP Rebars

Buildings ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 72
Author(s):  
Simona Coccia ◽  
Fabio Di Carlo ◽  
Stefania Imperatore
Keyword(s):  
Ad Hoc ◽  
Masonry Wall ◽  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Seismic Capacity ◽  
Seismic Behaviour ◽  
Safety Level ◽  
Dynamic Analyses ◽  
Out Of Plane ◽  
Vertical Bars

The out-of-plane behaviour of the walls as a consequence of an earthquake is the main vulnerability of existing masonry structures. In the case of rigid in compression not tensile resistant material, incremental dynamic analyses may be employed to evaluate the effective strength of a rocking element. When the seismic capacity of the wall is inadequate, retrofit interventions are required to assure an acceptable safety level. Conventional seismic retrofitting techniques on masonry walls influence the seismic performance of the element, which typically is modified in an out-of-plane bending behaviour. In this paper, analytical investigations are presented to investigate the possibility of a seismic retrofitting intervention able to increase the seismic strength of the wall without modifying its seismic behaviour. The analysed retrofitting technique consists in the application of composite vertical bars either in the middle section of the wall or at its external surfaces. The seismic behaviour of the retrofitted masonry wall is analytically evaluated by means of a parametric incremental dynamic analysis, carried out with an ad hoc in-house software. The effectiveness of the intervention is analysed in terms of level of seismic improvement, defined as the ratio between the seismic capacity of the reinforced and unreinforced walls.

Rocking in Presence of Cracking of Masonry Wall Piers

2017 ◽  
Vol 747 ◽  
pp. 678-685 ◽  
Author(s):  
Fabio di Carlo ◽  
Simona Coccia ◽  
Mario Como
Keyword(s):  
Energy Dissipation ◽  
Masonry Wall ◽  
Structural Systems ◽  
Masonry Building ◽  
Masonry Structures ◽  
Structural Components ◽  
Failure Condition ◽  
Triangular Region ◽  
Lower Triangular ◽  
The One

The wall pier represents the vertical element of multi-storey walls with openings, the main resistant structural components of a masonry building. Structural systems of wall piers and spandrels are required to sustain the in-plane seismic actions acting on the wall, opposing with their weights to the action of horizontal forces. The behavior of masonry constructions results to be very far from the one characterizing ductile structures, because of the lack of energy dissipation during the deformation. A strength resource of masonry structures, properly reinforced in order to avoid early local failures, consists in exhibiting rocking behavior, until a failure condition is attained. An investigation on the dynamic behavior of masonry wall piers is carried out by following Housner’s studies and properly introducing the effect of diagonal cracks, shown by typical post-earthquake cracking patterns. As a consequence, the system is characterized by the detachment of a lower triangular region that becomes ineffective during the development of the mechanism and does not oppose with its weight to the overturning. Finally, it is shown that the occurrence of diagonal cracks can be prevented by the execution of suitable retrofit interventions.

scholarly journals Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons

2018 ◽  
Vol 2 (3) ◽  
pp. 6-16 ◽  
Author(s):  
Elena Ferretti
Keyword(s):  
Ultimate Load ◽  
Masonry Wall ◽  
Experimental Results ◽  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Less Invasive ◽  
Entire Height ◽  
Out Of Plane ◽  
Seismic Forces ◽  
Frp Strips

Abstract One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.

scholarly journals Attaining a Beam-Like Behavior with FRP Strips and CAM Ribbons

2018 ◽  
Vol 2 (3) ◽  
pp. 7 ◽  
Author(s):  
Elena Ferretti
Keyword(s):  
Ultimate Load ◽  
Masonry Wall ◽  
Experimental Results ◽  
Seismic Retrofitting ◽  
Masonry Walls ◽  
Less Invasive ◽  
Entire Height ◽  
Out Of Plane ◽  
Seismic Forces ◽  
Frp Strips

One of the major concerns in the seismic retrofitting of masonry walls is that of increasing the ultimate load for out-of-plane forces. In multi-story buildings, these forces may originate from the hammering actions of floors, when the earthquake direction is orthogonal to the wall. A possibility for counteracting the out-of-plane displacements is retaining the wall by building some buttresses, that is, some beams lean against the wall and disposed vertically. Another possibility is to make the buttress in the thickness of the wall. In this second case, we must cut the wall for its entire height, realize the buttress, and restore the masonry wall around it. In both cases, the interventions are highly invasive. The first intervention also leads to increments of mass that enhance the attraction of seismic forces. The aim of this paper is to find a less invasive and lighter alternative for realizing buttresses. We proposed to use FRP strips and steel ribbons in a combined fashion, so as to realize an ideal vertical I-beam embedded into the wall, without requiring to cut the masonry. We also provided some experimental results for verifying the effectiveness of the model.

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