Additionally, we can represent that information graphically to facilitate the visualitation there is only a representation of the first 80th modes. Modal mass coefficient and modal participation factor in sap2000. Calculated story drift using the maximum inelastic response displacement. For modal response history analysis, sap2000 allows an explicit damping. It has even been codified in many of the codes of record. The effective modal mass provides a method for judging the significance of a vibration mode. A detailed and extensive procedure which describes the modeling, analysis, and design of a 3d steelframe pipe rack system. Modal mass k modal stiffness k g modal geometric stiffness f,f force or force vector f frequency z angular frequency participation factor p effective mass a dynamic amplification d,e rayleigh damping coefficients damping ratio in general scalar quantities are denoted by italics e.
Csi analysis and reference manual for sap2000, etabs and safe 2. How do i calculate the fixedmass participation ratio of the model. Interpreting the modal mass participating ratios table. Mass participation ratio technical knowledge base computers. These parameters are used in the determination of the factor phib which eventually is used in the interaction equations eqn. The third part of this volume, the sap2000 introductory tutorial manual, is intended to provide firsttime users with handson experience using the modeling, analysis and design features of sap2000. Guidelines and tutorial for modeling haunched steelgirder bridges. Example i general modeling techniques 2d shear wall analysis.
Sap2000 has a powerful design in steel, concrete and aluminum fully integrated, all available from the same interface used to model and analyze the model. As the modal mass participating factor is more than 75% in the higher mode, the considered structure is stiff for earthquake excitation. Sap2000 manual sap2000 is a program developed by the company csi, computer and structures, inc. My doubt is that modal mass coefficient and participation factor as per atc 40 are.
Concerning analysis with sap2000 and abaqus software. In addition, static and dynamic participation factors have been defined that allow the structural. Because the default number of mode shapes entered in sap2000 are 12. For the love of physics walter lewin may 16, 2011 duration. My guess is that ux, uy, and uz represent the mass participation of the translational mass. The design of aluminum and steel members permits initial sizing and an interactive optimization and design of concrete elements includes calculating the required number of steel reinforcing. Demonstration of dynamic lateraltorsional coupling in building structures ucla pxt, pyt, p. Learn about the sap2000 structural analysis and design program. Select the units you want to work with from the status bar at the bottom of the sap2000 window.
Sap2000 tutorials training videos, manuals and model files 38 gb civil engineering community from. The following guidance is for elastic dynamic analysis. Threedimensional static and dynamic analysis of structures. Turkish ts 5002000 r2018, mexican rcdf 2017, australian as 36002018 and korean kbc 2016. The fixedmass participation ratio may be calculated as follows. Check the mass participation to see if enough modes were included in the solution. Example of how to use the mass participation factor in. This should give you consistent modal participation factors. You can analyze any structures in this program, and even design element by element precisely with the known regulations aci in eu, rcdf in mexico, eurocode europe, etc. Sap2000 is a registered trademark of computers and structures, inc. The displacement demand of a 4story frame was 170 mm with a scale factor of 1. Seismic design of buildings worked examples worked examples presented at the workshop ec 8. Export the joint masses table to excel by selecting analysis results joint output joint masses sum all joint masses to find the total mass square the participation factor table and divide this value by total mass. Modal participation factor and modal mass coefficient for.
Advanced applied load options have been added for multistep static load cases. Users manual, online documentation help, dassault systemes usa. Go into define load cases modal cases define modal case change the number of mode shapes you want to consider. The allowable story drift should be greater than or equal to the design story drifts for each floor level. If modes 3, 6, 8 and 10 look like torsional modes, then this would probably confirm my assumption. Demonstration of lateraltorsional coupling in building.
Sap2000 training manual civil engineering community. Description and users guide, university of california, berkeley, ca. Pdf response spectrum analysis for irregular multi. Modes with relatively high effective masses can be readily excited by base excitation. Building is required to be provided with moment resisting frames detailed as per is.
Mini sap 2000 tutorial for an example beam hands on. Pushover analysis of steel structure using staad tn. As you said in sap2000 display tables, it gives the participation factors which is true but it. Under drift check, there are two checks to consider. Interpreting the modal mass participating ratios table from etabs posted on october 8, 2018 march 14, 2019 by engr dennis mercado i have not been modelling extensively in etabs this recently so this query from a former had my technical engine humming once more. Mass participation factor and its role in modal anlysis. You can change the units you are working with at any time and sap2000 will handle the conversion. I believe the current version of sap2000 explicitly calculates this and you may find. Effects of plastic hinge properties in nonlinear analysis.
Optimized modeling and design of structures using sap2000 presented by. Till now we are not considering the mass participation factor for targeting the modes. This allows the same link property to be used for multiple link objects that may, for example, represent different size. Modal participation factor and modal mass coefficient for the first natural mode in sap 2000 shz7 structural 6 jun 17 02. Csi etabs 11 modal analysis case eigen or ritz vectors for fundamental time periodfrequency duration. Sap90, sap2000, safe, floor and etabs are trademarks of.
The modal mass participation ratio is widely used as the metric to determine the relative significance of modes in a modal response spectrum analysis. However, in many cases the users manual does not clearly. Ppt pushover analysis powerpoint presentation free to. Fourth, the 90 percent mass participation rule, intended to assure accuracy of. A new nonlinear multistep static load case type has been added. As you said in sap2000 display tables, it gives the participation factors which is.
The modal participation factor i for mode i is mo ii li i 26 the modal participation vector is thus. The fixed mass participation ratio may be calculated as follows. The program starts with the period of the modecalculated to have the largest participation factor in the direction thatloads are being calculated x or y. How to calculate the relative contribution of each mode in. For example, asce 705 710 is at home, sorry, section 12. After running modal analysis, modal mass participation can be checked in etabs. Ive modeled a simple 2 dof structure in etabs then manually computed the. Seismic code requirements ucla henry samueli school of. Risa3d rapid interactive structural analysis 3dimensional version 7. My doubt is that modal mass coefficient and participation factor as per atc 40 are unitless values. This tutorial provides an introduction to the assignment of joint patterns. To identify the dimensionless parameters governing the coupled lateraltorsional response of the system, equation 2 can be rewritten as note that ey px p. Mass participation zthe force participation of each mode can be gauged by the mass participation factor.
Why does sap2000 divide the responses of structures into. Being an office building, the importance factor, i, is 1. Earthquake analysis with sap2000 earthquake analysis with sap2000 prepared by. The modal participation factor matrix i for mode i is m. And the software will limit it to that many number of modal r. Scaling factor for each ground motion should not be greater than 8. Square the participation factor table and divide this value by total mass. Modal periods and frequencies are compared in the following table 2. Start up screen of sap2000, select working unit to be tonm at dropdown menu. Sap2000 tutorial manual 3 building the model in sap2000 using templates 1. Lin ear and non lin ear static and dy namic anal y sis and. But if the first six modes only contribute 60% mass participation, and above 12 th mode also if for mode the mass participation factor is higher should we check with compressor harmonics upto that or not.
Local modes may disrupt the modal mass participation mode shapes. Modal mass coefficient and modal participation factor in. If so, then rx, ry and rz would likely represent the mass particiaption of the rotational mass moment of inertia. It is strongly recommended that you read this manual and work the tutorial before attempting a real project using sap2000.