Dear Friends & Colleagues,

For nearly 35 years, CSI software has been the universal choice of sophisticated engineering professionals for structural design and retrofitting. Today, as our nation enters this critical infrastructure rebuilding era, CSI stands ready to deliver the most productive and practical software available in the market—as we have since 1975. Offering advances in every facet, from powerful information processing to efficient numerical simulation, CSI products offer unmatched technology for engineering modeling, analysis, design, and project documentation.

The structural engineering profession is being summoned to rebuild our nation's freeways, bridges, schools, hospitals, and the infrastructure that drives our economy— to create jobs and to put America back to work. CSI’s commitment to the development of state-of-the-art structural engineering software has never been stronger. Reflecting more than three decades of development experience, CSI's innovations will continue to set the industry standard.

Please contact us or click here to learn more about CSI software products and training services. We look forward to hearing from you!

Sincerely,


Ashraf Habibullah, President & CEO
Computers & Structures, Inc.

 
     
 

IN THIS ISSUE:

TECHNICAL CORNER - THE MAGIC OF RITZ
SAP2000/BRIDGE - INTEGRATED 3-D BRIDGE DESIGN SOFTWARE
CSI SPONSORS EVENT - THE LIFE AND URDU POETRY OF GHALIB!
ONLINE SOFTWARE TRAINING - NEW DATES ANNOUNCED
CSI CARIBE SPREADS THE WORD IN LATIN AMERICA
CSI SPONSORS EERI SEISMIC DESIGN COMPETITION
CSI SPONSORS THE ENGINEERS ALLIANCE FOR THE ARTS

 

 
     
 

In the evaluation of the dynamic response of a structure, the engineer often must calculate the free vibration modes of the system. Traditionally this has been accomplished by conducting an Eigen analysis to produce the structural mode shapes and corresponding frequencies. These modes are then used to conduct the dynamic analysis.

Depending on the characteristics of the dynamic loading, many Eigen modes may have low participation and may contribute little or nothing to the dynamic response of the structure. This makes the Eigen analysis-based procedure inefficient because a significant numerical effort is wasted in calculating trivial modes.

In contrast, the Ritz analysis does not produce “exact Eigen vectors," rather Load Dependent Ritz (LDR) vectors. As the name suggests, these vectors are dependent upon the characteristics of the dynamic loading that is being applied. The net effect is that the only vectors calculated are ones which produce non-trivial contributions to the response of a structure when subjected to that dynamic load.

Ritz procedure offers computational efficiency because it requires calculation of fewer vectors and because the dynamic analysis algorithm also processes fewer vectors during the solution and recovery.

In an Eigen-based dynamic solution, several hundred modes may be needed for large systems to capture the mass participation percentage (typically 90 percent) required by many design regulations. The results then need further corrections due to missing mass vectors. The Ritz-based dynamic solution needs far fewer modes to achieve the required mass participation, and the missing mass is always automatically included in every set of Ritz vectors.

It is also important to note that although Ritz vectors are not Eigen vectors, they are all linear combinations of the Eigen vectors; therefore, the method always converges to the exact solution. The effectiveness of Ritz vectors is appreciable for any dynamic loading, but is most noteworthy when evaluating the effect of vertical ground motion, multiple-support excitation, or even the application of localized forces such as footfall or machine vibration.

The power of the Ritz technology has been effectively applied in linear and nonlinear applications, making Ritz an aspect of structural dynamics worthy of study.

For more technical information on Ritz vectors please see the CSI Analysis Reference Manual.

 
     
 

SAP2000/Bridge combines a versatile and intuitive bridge object-based user interface with the potency of CSI’s analytical engine, SAPFire®, to produce the most versatile and productive software package for designing, rebuilding and retrofitting our bridges and freeways. For more information about this product click here.

 
     
     
 

Lovers of Urdu poetry, especially our friends and colleagues in South Asia, will be pleased to know that Computers & Structures is sponsoring a festive afternoon celebrating the life and poetry of Mirza Ghalib, the beloved and perhaps greatest poet of the Urdu language. The event, held at the Indian Community Center in Milpitas, California, will feature highlights of Ghalib’s life and will study the impact of his renowned poetry. Various participants will present selected readings from his famous Diwan-e-Ghalib. For more information about ICC, click here.

To download a flyer about the event, click here.

 
     
     
 

Due to popular demand, new dates have been announced for SAFE and SAP2000/Bridge online training. You will experience live over-the-web training led by an expert CSI software instructor. Space is limited, so register early.

Introduction to SAFE v12- Reinforced Concrete

DATE
TIME (Pacific)
Thursday, April 9 1:00 pm - 2:30 pm  
Thursday, April 23 10:00 am - 11:30 am  
Thursday, May 7 10:00 am - 11:30 am  
Thursday, May 21 1:00 pm - 2:30 pm  

Introduction to SAFE v12 Post-Tensioned Concrete

DATE
TIME (Pacific)
Friday, April 10 8:00 am - 9:30 am  
Friday, April 24 1:00 pm - 2:30 pm  
Friday, May 8 10:00 am - 11:30 am  
Friday, May 22 1:00 pm - 2:30 pm  

Seismic Design of Bridges Using SAP2000 Bridge

DATE
TIME (Pacific)
Thursday, April 9 10:00 am - 12:00 pm  
Thursday, April 23 1:00 pm - 3:00 pm  
Thursday, May 7 1:00 pm - 3:00 pm  
Thursday, May 21 10:00 am - 12:00 pm  
 
     
     
 

The Fourth International Structural Engineering Seminar was hosted by CSI Caribe in Caracas, Venezuela, February 2-11, 2009. Engineers from all over Latin America attended the ten-day training which covered the concepts of concrete design, shear wall design, pushover analysis, nonlinear analysis, sequential construction, and slab and foundation design.

For more information about CSI Caribe, click here.

 
     
     
 

Computers and Structures, Inc. proudly sponsored the 6th Annual Undergraduate Student Seismic Design Competition at the 2009 EERI Annual Conference held in Salt Lake City, Feb 11-14, 2009. The event, organized by EERI's Student Leadership Council, drew 100 of the best of the next generation of earthquake engineers from 18 universities throughout the country. They designed, analyzed, and fabricated scale models of high-rise office buildings, using CSI software in most cases. The competition room was filled to capacity with cheering onlookers, both students and professionals. The students made presentations describing their creative and innovative designs and then conducted shaking table tests on the models.

The teams were ranked by their overall performance index, with Cal Poly San Louis Obispo placing first, Brigham Young University placing second, and Oregon State University placing third. Two special awards were also given: the Charles Richter Competition Spirit Award went to a one-man team from Brigham Young University, and the Egor Popov Innovative Design Award was given to the University of California Davis. For more information about the seismic design competition, click here.

 
     
     
 

Computers & Structures, Inc. has proudly presented a matching grant to the Engineers Alliance for the Arts (EAA). The grant supports EAA in their mission to instill passion and enthusiasm for structural engineering by introducing students to the technical, creative and artistic aspects of the profession. EAA’s eight week Student Impact Project brings members of the structural engineering profession together with high school students to teach them about art and engineering. These engineers make an incredible impact on the lives and futures of talented young people while bringing the profession to the forefront in a meaningful and exciting way.

Individuals and organizations are invited to make tax deductible donations to EAA. CSI will match all donations, dollar for dollar, that are received by June 30, 2009. For details please contact EAA Executive Director Antigone Trimis at 415.846.5743.

For more information about EAA click here.

 
     
 

SOFTWARE UPDATES

SAP2000: 12.0.2

ETABS: 9.5.1

SAFE: 12.1.1

CSICOL: 8.4.0


Perform 3D: 4.0.4

UPCOMING TRADE SHOWS AND CONFERENCES

April 1-4: NASCC Steel Conference & Exhibition
Phoenix Convention Center
Phoenix, Arizona

June 17-20: International Bridge Conference
The David L. Lawrence Conference Center
Pittsburgh, Pennsylvania

November 17-20: World Steel Bridge Symposium
Henry B. Gonzalez Convention Center
San Antonio, Texas



PRODUCT INFORMATION

 
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Copyright © 2009 Computers & Structures, Inc. SAP2000, ETABS, SAFE, PERFORM 3D and CSICOL are trademarks of CSI