scholarly journals Study on The Effect of Soft Story on Infill RC Frames Under Seismic Effect

2018 ◽  
Vol 13 (2) ◽  
pp. 79-91
Author(s):  
Mahesh Raj Bhatt ◽  
Prachand Man Pradhan ◽  
Sudip Jha
Keyword(s):  
Load Transfer ◽  
Linear Time ◽  
Time History ◽  
Seismic Demand ◽  
Bottom Part ◽  
Infill Wall ◽  
Analysis And Design ◽  
Soft Story ◽  
Regular Frame ◽  
Rc Frames

Construction practice of reinforced concrete (RC) frames infilled with unreinforced masonry is quite common now-days in urban cities in Nepal and elsewhere. Previous study shows the lateral load transfer mechanism is different than that of bare frames in infill buildings. Because of the unavoidable circumstances like elimination of central columns, elimination of infill wall in basement for parking purpose and reducing the size of frame members etc. may cause the particular story to be soft.In this study the infill RC frames with stiffness irregularity has been analysed with linear time history method using Gorkha-2015 earthquake as ground motion using structural analysis and design software (ETABS 2000 V.16). In total 8-numbers of 6-story RC infilled frames were analysed introducing the soft story in each story level respectively from basement to top. Regular frame was designed as per IS 1893:2002 load combination considering torsional effect. After analyse of bare frame, regular frame and irregular frames the global and story level seismic demand parameters were studied comparatively. Base/Story shear, Story displacement, inter-story drift and fundamental time period were the parameters compared taking regular frame as reference case.Results showed that, there is significant effect of location of irregularity on the seismic demand. The global and story level seismic demand is higher when the irregularity is introduced in bottom part of the buildings and further it showed that the lateral strength of RC frames get highly enhanced due to introductions of infill in analytical models.Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 2, 2017, page:79-91

Performance of Buildings Using Site Specific Ground Motion of Kolkata, India

2019 ◽  
Vol 10 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Amit Shiuly
Keyword(s):  
Seismic Waves ◽  
Linear Time ◽  
Alluvial Soil ◽  
Time History ◽  
Specific Time ◽  
Infill Wall ◽  
Site Specific ◽  
Open Ground ◽  
Immediate Occupancy ◽  
Almost All

Kolkata, capital of West Bengal, India, is presently congested with moderate to high rise buildings, and may undergo damage during future earthquakes due to the amplification of seismic waves by the soft alluvial soil. Further, most of the buildings are open ground storey (OGS), which is very vulnerable to earthquakes. Therefore, in the present study, the performance of some typical G+1, G+4 and G+9 storied buildings are analyzed using the available site-specific time history of the city by non-linear time history analysis (NLTHA). The analysis has been carried out for maximum considerable earthquake (MCE) and design basis earthquake (DBE) by both considering the stiffness of the infill wall (WI) and without considering stiffness of infill wall (WOI). The result signifies that, in almost all locations, the percentage of roof displacements obtained by site specific time history are more than the Indian codal compatible time history for both WI and WOI. Thus, performance will not be satisfactory for the buildings which are designed according to the Indian seismic code. The present study also corroborates that for almost all the buildings, the ground storey drift remains below immediate occupancy (IO) level during DBE and it varies IO to life safety (LS) level during MCE. However, all the storey drift are below Collapse Prevention (CP) limit. It is to be mentioned that for all the buildings the inter storey drift is higher than the Indian codal (IS-1893 (Part 1):2016) permissible limit (0.4%) during both DBE and MCE. However, the storey drifts result for WI buildings are comparatively lower than WOI buildings which are due to addition of stiffness of infill in each floor and fundamental modal spectral acceleration is lower.

scholarly journals Seismic Performance of a Three-Story Reinforced Concrete Building with Masonry Infill Walls and Friction Base Support

2021 ◽  
Vol 23 (1) ◽  
pp. 35-43
Author(s):  
Pamuda Pudjisuryadi ◽  
V.S. Prayogo ◽  
S.I. Oetomo ◽  
Benjamin Lumantarna
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Linear Time ◽  
Time History ◽  
Masonry Wall ◽  
Infill Wall ◽  
Infill Walls ◽  
Rc Structures ◽  
Masonry Infill ◽  
Masonry Infill Walls

The stiffness of masonry infill walls is commonly neglected in design practice of Reinforced Concrete (RC) structures. In fact, the stiffness of masonry infill wall may significantly influence seismic performance and dynamic behavior of RC buildings. In this research, influence of masonry infill walls to the structural performance of a three-story RC frame is investigated. In addition, possible application of friction-based support is also studied. Full 3D non-linear time history analysis is conducted to observe behavior of the structure under two-directional ground motion. In the analysis, any failed elements are removed subsequently from the model to avoid numerical analysis problem. The result shows that the placement of masonry infill walls can significantly influence the structural behavior of RC structure. Inappropriate placement of masonry wall may lead the building undergo soft-story mechanism. It is also found that the use of friction-based support can effectively improve the seismic performance of the building.

Comparison of Interstorey Drift in General RC Buildings in Pounding and No Pounding Case

2020 ◽  
Vol 2 (1) ◽  
pp. 40-47
Author(s):  
Anand Dev Bhatt
Keyword(s):  
Seismic Analysis ◽  
Linear Time ◽  
Time History ◽  
Case Analysis ◽  
Rc Buildings ◽  
Adjacent Buildings ◽  
Sufficient Distance ◽  
Earthquake Load ◽  
Interstorey Drift ◽  
Lower Height

 Inter-storey drift is an important parameter of structural behavior in seismic analysis of buildings. Pounding effect in building simply means collision between adjacent buildings due to earthquake load caused by out of phase vibration of adjacent buildings. There is variation in inter-storey drift of adjacent buildings during pounding case and no pounding case. The main objective of this research was to compare the inter-storey drift of general adjacent RC buildings in pounding and no pounding case. For this study two adjacent RC buildings having same number of stories have been considered. For pounding case analysis there is no gap in between adjacent buildings and for no pounding case analysis there is sufficient distance between adjacent buildings. The model consists of adjacent buildings having 4 and 4 stories but unequal storey height. Both the buildings have same material & sectional properties. Fast non-linear time history analysis was performed by using El-centro earthquake data as ground motion. Adjacent buildings having different overall height were modelled in SAP 2000 v 15 using gap element for pounding case. Finally, analysis was done and inter-storey drift was compared. It was found that in higher building inter-storey drift is greater in no pounding case than in pounding case but in adjacent lower height building the result was reversed. Additionally, it was found that in general residential RC buildings maximum inter-storey drift occurs in 2nd floor.

Concentrated plasticity modelling of RC frames in time-history analyses

2021 ◽  
Vol 243 ◽  
pp. 112716
Author(s):  
Eleonora Bruschi ◽  
Paolo M. Calvi ◽  
Virginio Quaglini
Keyword(s):  
Time History ◽  
Rc Frames

scholarly journals Seismic Response of RC Frames with a Soft First Story Retrofitted with Hysteretic Dampers under Near-Fault Earthquakes

2021 ◽  
Vol 11 (3) ◽  
pp. 1290
Author(s):  
Santiago Mota-Páez ◽  
David Escolano-Margarit ◽  
Amadeo Benavent-Climent
Keyword(s):  
Cost Effective ◽  
Far Field ◽  
Soft Story ◽  
Near Fault ◽  
Rc Frames ◽  
Story Drift ◽  
Number Of Cycles ◽  
Rc Frame Structures ◽  
Near Fault Earthquakes ◽  
Hysteretic Dampers

Reinforced concrete (RC) frame structures with open first stories and masonry infill walls at the upper stories are very common in seismic areas. Under strong earthquakes, most of the energy dissipation demand imposed by the earthquake concentrates in the first story, and this eventually leads the building to collapse. A very efficient and cost-effective solution for the seismic upgrading of this type of structure consists of installing hysteretic dampers in the first story. This paper investigates the response of RC soft-story frames retrofitted with hysteretic dampers subjected to near-fault ground motions in terms of maximum displacements and lateral seismic forces and compares them with those obtained by far-field earthquakes. It is found that for similar levels of total seismic input energy, the maximum displacements in the first story caused by near-fault earthquakes are about 1.3 times larger than those under far-field earthquakes, while the maximum inter-story drift in the upper stories and the distribution and values of the lateral forces are scarcely affected. It is concluded that the maximum displacements can be easily predicted from the energy balance of the structure by using appropriate values for the parameter that reflects the influence of the impulsivity of the ground motion: the so-called equivalent number of cycles.

scholarly journals Record-to-record variability and code-compatible seismic safety-checking with limited number of records

2021 ◽  
Author(s):  
Fatemeh Jalayer ◽  
Hossein Ebrahimian ◽  
Andrea Miano
Keyword(s):  
Seismic Hazard ◽  
Linear Time ◽  
Time History ◽  
Time History Analysis ◽  
Seismic Safety ◽  
Hazard Curve ◽  
History Analysis ◽  
Non Linear ◽  
Seismic Hazard Curve ◽  
Cloud Analysis

AbstractThe Italian code requires spectrum compatibility with mean spectrum for a suite of accelerograms selected for time-history analysis. Although these requirements define minimum acceptability criteria, it is likely that code-based non-linear dynamic analysis is going to be done based on limited number of records. Performance-based safety-checking provides formal basis for addressing the record-to-record variability and the epistemic uncertainties due to limited number of records and in the estimation of the seismic hazard curve. “Cloud Analysis” is a non-linear time-history analysis procedure that employs the structural response to un-scaled ground motion records and can be directly implemented in performance-based safety-checking. This paper interprets the code-based provisions in a performance-based key and applies further restrictions to spectrum-compatible record selection aiming to implement Cloud Analysis. It is shown that, by multiplying a closed-form coefficient, code-based safety ratio could be transformed into simplified performance-based safety ratio. It is shown that, as a proof of concept, if the partial safety factors in the code are set to unity, this coefficient is going to be on average slightly larger than unity. The paper provides the basis for propagating the epistemic uncertainties due to limited sample size and in the seismic hazard curve to the performance-based safety ratio both in a rigorous and simplified manner. If epistemic uncertainties are considered, the average code-based safety checking could end up being unconservative with respect to performance-based procedures when the number of records is small. However, it is shown that performance-based safety checking is possible with no extra structural analyses.

scholarly journals Tuned Mass Damper Design for Slender Masonry Structures: A Framework for Linear and Nonlinear Analysis

2021 ◽  
Vol 11 (8) ◽  
pp. 3425
Author(s):  
Marco Zucca ◽  
Nicola Longarini ◽  
Marco Simoncelli ◽  
Aly Mousaad Aly
Keyword(s):  
Nonlinear Analysis ◽  
Linear Time ◽  
Design Procedure ◽  
Time History ◽  
Tuned Mass Damper ◽  
Second Phase ◽  
Masonry Structures ◽  
Base Shear ◽  
Mass Damper ◽  
Linear And Nonlinear

The paper presents a proposed framework to optimize the tuned mass damper (TMD) design, useful for seismic improvement of slender masonry structures. A historical masonry chimney located in northern Italy was considered to illustrate the proposed TMD design procedure and to evaluate the seismic performance of the system. The optimization process was subdivided into two fundamental phases. In the first phase, the main TMD parameters were defined starting from the dynamic behavior of the chimney by finite element modeling (FEM). A series of linear time-history analyses were carried out to point out the structural improvements in terms of top displacement, base shear, and bending moment. In the second phase, masonry's nonlinear behavior was considered, and a fiber model of the chimney was implemented. Pushover analyses were performed to obtain the capacity curve of the structure and to evaluate the performance of the TMD. The results of the linear and nonlinear analysis reveal the effectiveness of the proposed TMD design procedure for slender masonry structures.

scholarly journals Displacement-based design of precast hinged portal frames with additional dissipating devices at beam-to-column joints

2021 ◽  
Author(s):  
Andrea Belleri ◽  
Simone Labò
Keyword(s):  
Design Methodology ◽  
Linear Time ◽  
Design Procedure ◽  
Time History ◽  
Structural System ◽  
Additional Degree ◽  
Speed Up ◽  
Column Joint ◽  
Displacement Based ◽  
Mechanical Devices

AbstractThe seismic performance of precast portal frames typical of the industrial and commercial sector could be generally improved by providing additional mechanical devices at the beam-to-column joint. Such devices could provide an additional degree of fixity and energy dissipation in a joint generally characterized by a dry hinged connection, adopted to speed-up the construction phase. Another advantage of placing additional devices at the beam-to-column joint is the possibility to act as a fuse, concentrating the seismic damage on few sacrificial and replaceable elements. A procedure to design precast portal frames adopting additional devices is provided herein. The procedure moves from the Displacement-Based Design methodology proposed by M.J.N. Priestley, and it is applicable for both the design of new structures and the retrofit of existing ones. After the derivation of the required analytical formulations, the procedure is applied to select the additional devices for a new and an existing structural system. The validation through non-linear time history analyses allows to highlight the advantages and drawbacks of the considered devices and to prove the effectiveness of the proposed design procedure.

Seismic Vulnerability Analysis of FRP Retrofitting Industrial Buildings

2015 ◽  
Vol 724 ◽  
pp. 353-357
Author(s):  
Jian Zhu ◽  
Ping Tan ◽  
Pei Ju Chang
Keyword(s):  
Seismic Vulnerability ◽  
Response Spectrum ◽  
Time History ◽  
Seismic Intensity ◽  
Fiber Reinforced Polymers ◽  
Infill Wall ◽  
Intensity Index ◽  
Industrial Buildings ◽  
Dynamic Time ◽  
Masonry Infill Wall

This study focus on derivation of such vulnerability curves using Fiber Reinforced Polymers technologies retrofitted conventional RC industrial frames with masonry infill wall. A set of stochastic earthquake waves which compatible with the response spectrum of China seismic code are created. Dynamic time history analysis is used to compute the random sample of structures. Stochastic damage scatter diagrams based different seismic intensity index are obtained. Seismic vulnerability of FRP-reinforced RC industrial frames is lower than unreinforced frames obviously, and seismic capability of frames using FRP technologies is enhanced especially under major earthquake.

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