Seismic hazard control in tall RC buildings providing shear walls or viscous dampers (original) (raw)
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EARTHQUAKE RESISTANT TECHNIQUES AND ANALYSIS OF TALL BUILDINGS
International Journal of Research in Engineering and Technology, 2015
The tall buildings are more flexible than the shorter buildings and they are sensitive to a different frequency range in the earthquake excitation. The earthquake success of tall buildings is reinforced by studies using average properties of earthquake and typical properties of tall buildings and there are no special earthquake hazards that arise simply as a consequence of height. The purpose of this paper is to discuss about different analysis methods, base isolation and soil structure interaction. Analysis method is used for a large variety of tall building configurations comprising slabs, beams, columns, foundations, walls, etc. Base isolation is a collection of structural elements which should substantially separate a superstructure from its substructure resting on a shaking ground which protects the integrity of building or non-building structures. It is one of the most powerful equipment's of earthquake engineering which uses the passive structural vibration control technologies. Soil Structure Interaction is the process in which the response of the soil influences the motion of the structure and the motion of the structure influences the response of the soil. General goal of the Soil Structure Interaction analysis is to calculate seismic response of structure bases on seismic response of free field.
IRJET, 2022
The damage to structures, when shaken by an earthquake, is due to factors like too much load on the structure (caused by post plan approval modification- like a 10 storey building in Ahmedabad which had a terrace garden cum pool and so it collapsed in the Jan 2000 Gujarat earthquake- though all equally tall structures all around it did not collapse); poor distribution of structural load creating joints or walls which give way under the sudden excess load due to vibration; poor foundations- too shallow for the height of the structure, built on land reclaimed from water bodies but soil not compacted etc. This shows how necessary it is to follow the building code prescribed for a given area/ region by the government. In earthquake prone areas like Japan, Indonesia, California etc. some techniques have been used which enable the structure to reduce the amplitude of vibrations by making the foundation or load bearing structure move as if Lead rubber bearing is used. There are also prescribed designs for the RCC framework and the way load is transmitted to the foundations by interlinking etc. The earthquake resistant structure has made possible to guarantee a better performance of buildings, when they are subjected to seismic actions. Therefore it is convenient that current codes for design of building become conceptually when defining the various parameters governing the structure exposure conditions, geological conditions of proposed site, topographical parameters, geological parameters that includes: soil type, bearing capacity of soil The purposed of this work is to study analysis, design and estimate of high rise structure in various zones. And also compare the earthquake resistant structure and lead rubber bearing structure for same zones, if we can compare this building structure we can find out difference in construction cost also which is economical safe for us.
SEISMIC PERFORMANCE OF SETBACK RC BUILDINGS WITH SOIL STRUCTURE INTERACTION
IRJET, 2022
In high rise framed structures, harm from seismic activity ground motion generally initiates at locations of structural weaknesses present in the lateral load resisting frames .The performance of high rise framed structures during strong seismic activity depends on the factors including distribution of mass, stiffness, and strength among the horizontal and vertical planes of structures. In certain cases, these weaknesses may arise due to discontinuity in stiffness, mass among adjacent storeys. Such discontinuity among stories are frequently associated with abrupt variations in the frame geometry alongside the height of structure. A common variety of vertical geometrical irregularity in building structures arises is the presence of setbacks, i.e. the presence of abrupt decrease of the lateral measurement of the structure at specific levels of the elevation. This structure group is recognised as ‘setback building’. This structure form is attractive and more popular in current high rise structure building mostly since of its functional and artistic architecture. Stepped structure is the one with vertical geometric irregularity, where the horizontal dimension of the lateral force resisting system in any storey is extra than 150% of that in adjacent storey. These structural irregularity isn’t acceptable from stability point of view, as seismic activity has proven to affect the structure in case of seismic activity. All the buildings during seismic activity is proven to be susceptible but the structures with soft storey configuration are being found to be mostly susceptible during seismic activity. Shortage of plain ground in mountainous regions and urge of mining, lead us to build asymmetrical constructions in the hills. Thus, the danger factor of these asymmetrical buildings rises sharply as even the base of the buildings becomes inclined at slope. This deadly combination of geometric irregularity, mass irregularity, stiffness irregularity makes the buildings too much weak to last during seismic activity. Hence, it is important to study the responses of such buildings to make such buildings seismic -resistant and avoid their downfall to save the damage of life and property.
New structural seismic protection for high-rise building structures
Journal of Vibroengineering, 2020
Presented Structural Seismic Isolation Method (SSIM) aims to provide high safety for Highly Reliable Structures (HRS) against strong earthquakes including near-fault and long-period ground motions. The examined structure is converted to Structural Seismic Isolation System (SSIS) by the SSIM method which exhibited inverse pendulum behaviour. For this purpose, structure foot base and foundation contact surfaces have been designed as any curved surfaces (spherical, elliptical, etc.) depending on the earthquake-soil-superstructure parameters and this contact surfaces have been separated by elastomeric (lead core rubber or laminated rubber bearings) seismic isolation devices. It would allow the structure foot base to turn around gyration centre through rubber bearing contact and maintains similar behaviour to the super-structure. SSIS system provides the possibility of keeping the natural-period of the structure in a larger interval, which is greater than the predominant-period of the ma...
2020
Earthquakes can occur at any time especially in the Philippines, a country located in the Pacific Ring of Fire. To ensure safety of occupants, structures need to be designed to withstand earthquakes with minimal to no damage. The study investigates the seismic response of a ten-story reinforced concrete hospital building. The building was designed following the specifications stated in the 2015 National Structural Code of the Philippines. Time history analysis was conducted using Kantan software to determine the response of the structure in terms of story drift, inter-story drift, story shear, and maximum story acceleration. The design earthquake waves used were El Centro and Hachinohe. The results show that the installation of base isolation system significantly reduced the responses of the structure. Story drift reductions ranging from 3.10% to 60.29% and story drift amplifications ranging from 17.72% to 77.57% were observed. Inter-story drift reductions were observed to range from 41.98% to 77.48%. Story shear reductions ranged from 42.00% to 78.93% and maximum story acceleration reductions ranged from 27.66% to 69.17%. Generally, the results showed that the response of the structure was reduced following the application of the base isolation system. The behavior of the structure as a single-degree-of-freedom system is also shown by the closeness of the story drift values. The energy dissipation by lead dampers on the base isolation system resulted in the reduced values for inter-story drift.
PERFORMANCE ANALYSIS OF TALL RCC STRUCTURE THOSE ARE EARTHQUAKE RESISTANT
Concepts Books Publication, 2018
Earthquakes, even though they occur rarely, induce inertia forc% which is dynamic and complex. Moreover, they are sometimes so devastating that it is worth going into the depth of understanding them. The current work is one step towards understanding the complex effects of this dynamic force particularly on low rise RC structures which are found in almost all parts of the world. During 2001 Bhuj earthquake of India, a major damage was observed in RC framed structures at Ahemdabad which were in the range of G+3 to G+7 storey. Most of the buildings were having a normal grid of 3m x 3m column spacing with a storey height of 3m. Hence the present work, which is expected to act as a guide line for Civil and Structural Engineers in smaller towns and cities where expert advice may not be easily available, is devoted to RC framed structures ranging from G+3 to G+ 7 storeys. Out of the various factors affecting the earthquake and dynamic response of RC framed structures, in the current study, the shape of the column is considered to be one of the factors. The G+7 storey frame without the consideration of brick infill is subjected to push over analysis. The performance point for rectangular and equivalent square shaped cross section of columns is studied. The study incorporates two variations in the overall plan dimensions - 6m x 6m and 6m x 9m having four panes each of 3m x 3m and 3m x 4.5m respectively. The same set of models are also studied with brick infill walls modeled as 2D finite elements and equivalent strut. The performance point obtained from the push over analysis is considered as a measure of performance. Parameters like base shear, roof displacement, number of plastic hinges, severity of hinges, effective damping, etc. are compared for the mathematical models at performance point.
Effect of Shock Absorbers in Enhancing the Earthquake Resistance of a Multi-storeyed Framed Building
Lecture notes in civil engineering, 2020
The concept of base isolation systems has gained wide spread acceptance in enhancing the earthquake resistance of a structure. To accomplish the predicted behaviour of the base-isolated buildings, the design for base isolation system is regarded as the dominant factor. The base isolation of the structure basically reduces the storey shear and acceleration and increases time period, storey displacement and storey drift inducing flexibility in rigid structure by dissipating energy to foundation. For the study, three framed structures in zone-V with vertical and horizontal irregularity having G+10 storey have been analysed for its seismic behaviour with and without isolator using ANSYS. The analysis incorporating earthquake load is based on the seismic coefficient method as described in IS 1893: 2002. The study has been conducted in complete conformity with various provisions in Indian Standards as Code of Practice for plain and reinforced concrete IS 456-2000 [1].
Mitigation Techniques for Seismic Protection of RC Buildings with Open Ground Storey
Construction of buildings with open ground storey is being practiced on a large scale in many countries around the world and also in developing countries such as India to facilitate the increasing need to provide parking space due to increasing population and unavailability and high costs of land in urban areas. Open Ground Storey (OGS) buildings are those type of buildings in which the ground storey is left open without the provision of infill walls in between the columns of the ground storey and infilled in all the upper stories thus introducing stiffness irregularity in the building making them vulnerable to earthquakes especially when located in higher seismic zones. It was observed that most of the buildings damaged during the past earthquakes like the Bhuj earthquake of 2001, were due to presence of open ground storey. Hence strengthening of buildings with such irregularity is the need of the hour inorder to avoid their poor performance during earthquakes in future and thus sa...