Comparison of Base Shear for Forced-Based Design Method and Direct Displacement-Based Design Method

10.29007/lft5 ◽  
2018 ◽  
Author(s):  
Bijal Chaudhri ◽  
Dipali Patel

The Seismic design of structure has conventionally been force based. Displacement is the major factor for the damage rather than force. The alternative procedure for seismic design, which becomes more popular, is performance based design method. Displacement is global parameter of performance based design method. Direct displacement based design method has been used for seismic design of structure. The paper attempts to design moment resisting RC-frame using Displacement based design method and Forced based design method. 15-storey building with shear wall has been taken for parametric study. The parameter like base shear and lateral load distribution are taken for the study. It is observed that base shear of RC building calculated by DDBD is less compared to FBD.


2011 ◽  
Vol 255-260 ◽  
pp. 2555-2559
Author(s):  
Zhen Sun ◽  
Wei Qing Liu ◽  
Shu Guang Wang ◽  
Ding Zhou ◽  
Dong Sheng Du

A simple and efficient direct displacement-based design (DDBD) method is introduced to base isolated (BI) structures. Assuming the vibration mode of superstructure to be the shear type and considering the BI structure to be an equivalent single degree of freedom (ESDOF) system with spring and damper at the seismic isolation layer. The acceleration response spectrum in Chinese code is converted to displacement response spectrum. Corresponding to the design displacement, the equivalent period is obtained. The relationship of the deign displacement, equivalent period, equivalent stiffness and base shear of the system can be derived from the given formulations. Then, the distribution of the base shear along the floors is obtained. This method has been applied to the design of a 12-story BI structure with lead rubber bearings in high intensity zone in Suqian city, Jiangsu province. The results show that the method is feasible for the design of BI structures.


2012 ◽  
Vol 594-597 ◽  
pp. 795-799
Author(s):  
Gui Tao Chen ◽  
De Min Wei

A displacement-based optimization design method of RC structure was proposed by combining direct displacement-based design method with nonlinear programming technique. To avert the influence of target displacement, the stationary constraint displacement was presented, and the target displacement can be updated during the optimal design process. Principle of virtual work and Gaussian integral method was employed to simplify the explicit relationship between horizontal displacement and the section dimension. Comparison analysis of the local optimal results corresponding to different displacement shapes was conducted to achieve global optimal design. The numerical tests presented demonstrate the computational advantages of the discussed methods and suggesting that the proposed method is a reliably and efficiently tool for displacement-based optimal design.


2016 ◽  
Vol 32 (2) ◽  
pp. 843-859 ◽  
Author(s):  
Cuiyan Kong ◽  
Mervyn J. Kowalsky

Damping scaling factors (DSFs) play an important role in direct displacement-based design (DDBD) as they provide a means to establish displacement response spectra for damping values beyond 5%. Response spectra for multiple damping values are needed for DDBD as the approach relies on equivalent linearization, expressed in the form of effective stiffness and equivalent viscous damping, to establish design forces for prescribed performance limit states. In the past, DSFs based on the Eurocode have been employed for DDBD; however, recent research has resulted in more robust DSF models. This paper examines the accuracy of the current DSF equation used in DDBD across the parameters that are important for structural design. A nonlinear regression analysis is performed based on the data obtained by the Rezaeian et al. (2014) model, and a base shear adjustment factor (SAF) is proposed for application to the DDBD base shear equation.


2020 ◽  
Vol 10 (11) ◽  
pp. 3889
Author(s):  
Martina Sciomenta ◽  
Vincenzo Rinaldi ◽  
Chiara Bedon ◽  
Massimo Fragiacomo

Structures under seismic excitation undergo different inter-story drift levels that can be associated to damage of both structural and non-structural elements, and thus to the expected losses. The Modal-Displacement Based Design (DBD) procedure, in this regard, has been developed to fix major issues of Force Based Design (FBD) approaches, thus to design multi-story buildings in which the inter-story drift can allow one to control damage mechanisms. In this paper, the conventional Modal-DBD methodology is applied to multi-story timber buildings constructed using the Blockhaus technology. Given their intrinsic geometrical and mechanical features (i.e., stacking of logs, door/window openings, gaps and friction mechanisms, etc.), dedicated methods of analysis are required for them, compared to other wooden structures. A three-story case-study Blockhaus system of technical interest is thus presented for the assessment of Modal-DBD calculation steps. As shown, special care must be spent for the selection of convenient inter-story drift limits that in general should reflect the characteristics of the examined structural typology. The backbone parameters are thus collected for each shear-wall composing the 3D Blockhaus building, based on refined Finite Element (FE) analyses of separate log-walls. The overall results of the Modal-DBD process are thus finally assessed by means of a Push-Over (PO) analysis, carried out on a simplified 3D FE model of the examined multi-story structure. The comparison of FE predictions, as shown, demonstrates that reliable estimates can be obtained when the Modal-DBD procedure is applied to timber Blockhaus systems. In particular, base shear loads can be estimated with good accuracy, while the corresponding top displacements are slightly overestimated (with up to +10%–14% the expected values, for the collapse prevention performance level).


2019 ◽  
Vol 19 (3) ◽  
pp. 162
Author(s):  
Annisaa Dina Puspita ◽  
Anis Rosyidah

The Force Based Design (FBD) and the Direct Displacement-Based Design (DDBD) are methods for designing seismic-resistant buildings. Building structures designed, are expected to be suitable with the purpose and usefulness of a building. For this reason, this study compares the performance of dual system structures using the DDBD and FBD methods that aim to prove better performance with consideration of safety against users during an earthquake. This research method uses design analysis method to compare the value of the base shear force, reinforcement ratio, and performance level using software for static nonlinear pushover analysis. The results showed the value of the base shear force x direction of the DDBD method was 17.57% smaller than the FBD method, whereas for the y direction the DDBD value was greater than 9.38% of the FBD. The value of the reinforcement ratio of the beam, column and shear wall results is greater DDBD than FBD. The actual drift of the DDBD and FBD methods is slightly different. So that both are at the same level of performance, namely damage control. The performance level has not reached the performance target of life safety design in DDBD, but the structure has met the level performance requirements for offices.


Author(s):  
Anagha Girish Malu ◽  
Satyabrata Choudhury

The Direct Displacement-Based Design (DDBD) method has become a popular seismic design tool for structures. It takes drift as the performance criterion while designing structures. This method overcomes the shortcomings of the traditional force-based seismic design method, which considers peak force as the design parameter. In terms of structural damage, deflection is a better indicator, and hence, DDBD is a more acceptable method for seismic design. In this paper, a 12-story RC frame building with supplemental damping has been designed and investigated using a direct procedure of calculation, while considering the displacement-based design method. The performance of building with and without viscous dampers for a particular performance level has been compared. The effects of the non-linearity of dampers have also been discussed, and the effect of constant and story proportional drift proportional damper forces have been investigated. The results of various cases have been compared. It has been found that drift proportional story shear proportional carried damper design leads to construction economy.


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