Rocking shear wall foundations in regions of moderate seismicity (original) (raw)
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The Structural Design of Tall and Special Buildings, 2012
A practical application of 'beam on nonlinear Winkler foundation' approach has been utilized in this paper for a case study on seismic performance of concrete shear wall frames to assess the soil-foundation-structure interaction effects. A set of 3-, 6-, 10-and 15-story concrete shear wall frames located on hypothetically soft, medium and hard soils were designed and modeled using the OpenSees platform. The numerical model of each frame was constructed employing the distributed and lumped plasticity elements as well as the flexure-shear interaction displacement-based beam-column elements incorporating the soil-footing interface. Pushover analysis was performed, and the results were studied through two code-based viewpoints: (a) force-based design and (b) performance-based design. A comparison was made afterwards between the frame behaviors in the fixed-/flexible-base conditions. The results indicate some degree of inaccuracy in the fixed-base assumption, which is regularly applied in analysis and design practice. The study emphasizes on how the fixed-base assumption overestimates the design of the wall element and underestimates the design of the connected moment frame.
Effect of Different Shear Wall Configurations on Seismic Response of a Moment-Resisting Frame
European Scientific Journal, 2014
Use of shear walls in RC buildings is one of the most commonly used strategies for earthquake mitigation. To avoid torsion in buildings, shear walls must be placed symmetrically in plan. In this paper, a five-storey RC building located in seismic zone-V is considered with four shear walls. Five different configurations of shear walls viz. bare frame, shear wall symmetrically placed at exterior bays (centrally), at core and adjacently placed in exterior of the building, are considered. These frames are analysed for seismic forces to assess performance in terms of base shear, storey drift, member forces and joint displacements. The frame with shear walls at core and centrally placed at exterior bays showed significant reduction of order 29% to 83% in lateral displacement. The reduction in bending moments is approximately 70% to 85% for interior and perimeter columns respectively. Shear and axial forces in columns have reduced by 86% and 45% respectively. Based on such results, the best placement of shear walls in building plan is suggested.
A REVIEW ON PERFOMANCE OF SHEARWALL & BRACINGS TO MEET EARTHQUAKE FORCES
isara solutions, 2020
During the Earthquake the building may get affected badly structurally and it needs rehabilitation or retrofitting as soon as possible. Columns, Beams and Slabs shall be retrofitted by certain methods. At some places, Shear Walls & bracings were also constructed, which were needed to support the structure and make the structure safe for further use. It was observed that the introduction of shear wall & brace members to retrofit a beam-column joint results in increment of load carrying capacity. Shear wall is a structural member designed to counteract the lateral forces acting on a structure. These walls are more important in seismically active zones when shear forces on the structure increases due to earthquakes. Steel braced frame is one of the structural systems used to resist earthquake loads in multistoried buildings. In the present study, the behaviour study of shear walls and braced system is done to retrofit a 15-storey structure by performing static and dynamic analysis on ETABS software. A comparative study was done based on displacement and modal mass participation ratio. It is found that brace and shear wall are more effective if provided along the periphery of structure and it is enough to raise them up by mid height of the building.
Innovations in Sustainable Earthquake Resisting Rocking Wall-Frames
Journal of Rehabilitation in Civil Engineering, 2018
This paper introduces a novel design concept for the development of efficient, sustainable Rocking-Wall Moment Frames (RWMFs) under seismic conditions. The proposed concepts lead to a novel structural configuration with provisions for Collapse Prevention (CP), Self-Centering (SC), reparability, performance control (PC), damage reduction, and energy based seismic analysis. It introduces the merits of design led analysis (DLA) over the traditional methods of approach, followed by the development of a lateral resisting system that is more efficient than its conventional counterparts. The fundamental idea behind the proposed methodology is that seismic structural response is mainly a function of design and construction, rather than numerical analysis. In design led analysis the rules of mechanics and structural design are induced rather than followed .The new system is a combination of grade beam restrained moment frames and articulated shear walls, tied to each other by means of post t...
Journal of Innovations in Engineering Education
It is observed during the past earthquakes, buildings in hilly regions have experienced high degree of damage leading to collapse though they have been designed for safety of the occupants against natural hazards. Hence, while adopting practice of multistory buildings in these hilly and seismically active areas, utmost care should be taken for making these buildings earthquake resistant. For the buildings on sloping ground, the height of columns below plinth level is not same which affects the performance of building during earthquake. Hence to improve the seismic performance of building shear walls play very important role.It is very necessary to determine the most effective location of shear walls. Shear wall arrangement must be accurate, because if not, it will cause negative effect instead. This paper is aimed at predicting the effect of positioning RC shear wall of different shape on the structural response of RC building resting on sloping ground. Eight models have been prepar...
Effective of Earthquake load on Behavior of Rectangular Shear Wall in RC Frame Building
Structural walls, or shear walls, are elements used to resist lateral loads, such as those generated by wind and earthquakes. Structural walls are considerably deeper than typical beams or columns. This attribute gives structural walls considerable in-plane stiffness which makes structural walls a natural choice for resisting lateral loads. In addition to considerable strength, structural walls can dissipate a great deal of energy if detailed properly. Walls are an invaluable structural element when protecting buildings from seismic events. Buildings often rely on structural walls as the main lateral force resisting system. Shear walls are required to perform in multiple ways. Shear walls can then be designed to limit building damage to the specified degree. The load-deformation response of the structural walls must be accurately predicted and related to structural damage in order to achieve these performance goals under loading events of various magnitudes. The applied load is generally transferred to the wall by a diaphragm or collector or drag member. The performance of the framed buildings depends on the structural system adopted for the structure The term structural system or structural frame in structural engineering refers to load-resisting subsystem of a structure. The structural system transfers loads through interconnected structural components or members. These structural systems need to be chosen based on its height and loads and need to be carried out, etc. The selection of appropriate structural systems for building must satisfy both strength and stiffness requirements. The structural system must be adequate to resist lateral and gravity loads that cause horizontal shear deformation and overturning deformation. The efficiency of a structural system is measured in terms of their ability to resist lateral load, which increases with the height of the frame. A building can be considered as tall when the effect of lateral loads is reflected in the design. Lateral deflections of framed buildings should be limited to prevent damage to both structural and nonstructural elements. In the present study, the structural performance of the framed building with shear wall will be analysis. In this paper, the structural performance of the RC framed building with Rectangularshear wall in will be analysis. The importance of the shear wall in resist the wind and earthquake load are study, the effect of the shear walls on the conventional frame system. The best location of shear wall are near center of mass and center of gravity .The improvement in the structural performance of the building with frame system by using shear wall is study.
ECONOMICAL PLACEMENT OF SHEAR WALLS IN A MOMENT RESISTING FRAME FOR EARTHQUAKE PROTECTION
Shear walls are one of the most basic lateral load resisting elements in an earthquake resistant building. To avoid torsion in buildings, shear walls must be placed symmetrically in plan. In this paper, a five-storey RC building located in seismic zone-V is considered with four shear walls. Five different configurations of shear walls viz. bare frame, shear wall symmetrically placed at exterior bays (centrally), at core and adjacently placed in exterior of the building, are considered. These frames are analysed for seismic forces to assess performance in terms of base shear, storey drift, member forces and joint displacements. The frame with shear walls at core and centrally placed at exterior bays showed significant reduction of order 29% to 83% in lateral displacement. The reduction in bending moments is approximately 70% to 85% for interior and perimeter columns respectively. Shear and axial forces in columns have reduced by 86% and 45% respectively. Then in order to make our building economically feasible we curtailed the top and second topmost storeys of our building and hence accordingly drew dawn the results in this paper.
Comparison of Shear Walls and Moment-Resisting Frames in Earthquake Resisting Buildings’ Design
Proceedings of International Structural Engineering and Construction
The rapid growth of urban population and limited land space have greatly influenced the development of high-rise structures. Lateral loads have an important effect on the design as the building height increases. In order to resist lateral loads, safety and minimum damage should be the prime concern when designing tall buildings. To meet these requirements, the structure should have adequate lateral strength and lateral stiffness and sufficient ductility. Among the various structural systems, shear wall systems or moment resisting frame systems could be a point of choice for designers. Thus, it is important to review and observe the behavior of these systems under seismic effect. This study compared the seismic response of the above structural systems using a case study application at variable seismic zones (Zone 2B, Lebanon Zone, Zone 3, and Zone 4) and at different building stories (Eight and 12-story building). The seismic response is measured in term of time-period, maximum story...
SEISMIC PERFORMANCE COMPARISON OF MID-RISE MOMENT RESISTING FRAME AND SHEAR WALL SYSTEM
Nowadays, RC structural systems are being used in construction industry worldwide. The observed response of medium rise building, based on post-earthquake damage assessment reports, during the latest earthquakes in the USA, Chile, Mexico and Japan have indicated that buildings including shear walls and dual structural systems behave considerably better during strong shaking. The viewpoint that shear walls are inherently brittle is still held in many countries (correspondingly in the codes) as a consequence of failures in poorly detailed RC walls. In this investigation, several RC frames, with and without shear walls, are designed according to the seismic codes, and then their nonlinear duplicates are exposed to a set of severe quakes. The time history nonlinear analyses results of these prototypes are then used to probe the effect of the existence of shear walls through using performance based design method. It is concluded that in general the existence of shear walls results in a noteworthy decline in the seismic deformation demand. These changes happened in both the plastic rotations in main RC structural members and the inter story drifts ratio. Hence, it is concluded that the existence of shear walls mostly improves the safety of medium rise RC frames within the assessment framework of performance based design codes such as ASCE41 (2006).
Earthquake response analysis of yielding structures coupled with vertically restrained rocking walls
Earthquake Engineering and Structural Dynamics, 2018
This paper investigates the inelastic response of a yielding structure coupled with a vertically restrained rocking wall. The paper first derives the nonlinear equations of motion of a yielding oscillator coupled with a vertically restrained rocking wall, and the dependability of the one-degree of freedom idealization is validated against the nonlinear time-history response analysis of a well-known nine-story moment-resisting steel frame that is coupled with a stepping, vertically restrained rocking wall. While, the coupling of weak building frames with rocking walls is an efficient strategy that controls inelastic deformations by enforcing a uniform interstory-drift distribution, therefore, avoiding mid-story failures, the paper shows that even for medium-rise buildings the effect of vertical tendons on the inelastic structural response is marginal, with the exception of increasing the vertical reactions at the pivoting points of the rocking wall. Accordingly, the paper concludes that for medium-rise to high-rise buildings , vertical tendons in rocking walls are not beneficial.