Be Structural Newsletter
Hello and welcome to our latest Be Structural Newsletter.
With the launch of V8i Bentley has started to introduce significant innovation and workflow improvements. The structural products are, of course, part of the V8i release; please read more in "New Releases" below. Additional articles in this newsletter include:
We hope you find the newsletter informative. If you would like to comment on the newsletter, its topics or content, please do so; we welcome your feedback!
Bentley provides products for particular industries to make the lives of engineers easier by tailoring the workflow to the type of structure they are designing. This provides an increase in productivity.
Our latest product, STAAD(X).Tower, helps engineers generate self-supporting towers, guyed towers, and monopoles using its parametric setup wizards. It constructs the physical model and categorizes the panels, legs, horizontals and bracing members with orientations without manual intervention. The structure can easily be edited to achieve the desired shape and configuration.
With STAAD(X).Tower, external components like antennas, appurtenances, and platforms can easily be attached and can generate wind, ice, and seismic loads following the TIA codes along with other standard reference loads. The robust analysis and design engine (as per TIA-222-F and TIA-222-G codes) helps to minimize efforts to obtain the analysis and design results. It also offers a vast range of post-processing graphs and diagrams.
STAAD(X).Tower provides a built-in library of standard bracing patterns with an extended facility to create and store user-defined bracing patterns for future use. It also treats a set of analytical members as a group. It automatically considers the set of individual analytical members of the tower legs and bracings as single physical members based on certain criteria. This provides smooth automatic generation of an analytical structure for any user-defined physical model and increases productivity by providing a library of reusable bracing patterns.
Additionally, STAAD(X).Tower provides a customizable and user-friendly report generation facility and also ensures bi-directional interoperability with other STAAD products.
View the product tour video.
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Significant Enhancements for Structural V8i Release
The recent company-wide launch of V8i, which included our structural products, is the next step to true interoperability. In fact, the “i” in V8i stands for the core capabilities of this launch and includes:
- Intuitive design modeling
- Interactive dynamic views
- Intrinsic geo-coordination, which offers the ability to locate files in Bentley’s ProjectWise or in Google Earth
- “Incredible” project performance
- Interoperability
Our analysis and design products, including RAM, STAAD, and our nuclear piping solution, AutoPIPE, were part of this release. In addition, our detailing package for steel, ProSteel, and our BIM offering, Bentley Structural, are part of this release.
Some of the highlights are noted below.
STAAD.Pro:
- Nuclear design to the ASME NF Design Codes
- Wind loading to the Russian SNiP 2.01.07-85 "Loads and Actions"
- Enhanced dynamic deflection animation
For more read this blog entry.
AutoPIPE Nuclear:
- Comprehensive analysis capability, including ASME NB 3600 Class 1, ASME NC 3600 Class 2, ASME ND 3600 Class 3, material properties database, Class 1 components and joint type, rupture stress criterion, and comprehensive fatigue evaluation
- Bidirectional integration with STAAD.Pro for combined piping and structural analysis for more accurate engineering designs.
For more read this blog entry.
RAM Concept:
- Eurocode 2:2004 (with TR43 2nd ed. and UK National Annex)
- Design column strip for column strip + middle strip forces
- Improved reinforcement layout
For more read this blog entry.
RAM Structural System:
- Buckling restrained braces
- Semirigid, flexible and pseudo-flexible diaphragms
- Boundary element design for concrete shearwalls
More information will follow on our V8i releases and we will be holding eSeminars throughout December and the first quarter to highlight the V8i structural products.
The first one took place for the RAM Structural System on December 10, 2008. Nearly 300 attendees show that there is great interest in this product. View the recording of this eSeminar titled "RAM Structural System - Seismic Advances 2008" now.
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Contributions from the Structural Team
The Direct Analysis Method in AISC 360-05
by Allen Adams, P.E., S.E., S.E.C.B
Chief Structural Engineer, RAM / Bentley
Member of AISC 360 Task Committee on Stability
The prominence of the Direct Analysis Method in AISC 360-05 has raised awareness of the need to consider stability and second-order effects in the analysis of building structures. The most dominant of these are:
- P-D
- P-d
- Structure Out-of-Plumbness
- Member Out-of-Straightness
- Residual Stresses
P-D has reference to the effects of the vertical loads acting on the laterally displaced structure. Moments are induced into the structure equal to the total vertical load P times the structural displacement D.
P-d has reference to the effects of the axial load in a member subject to a deflection (curvature) between its endpoints. Moments are induced in the member equal to the axial load P times the member deflection d.
Structure Out-of-Plumbness is a result of construction tolerance. The AISC Specification has a construction tolerance of L/500. That is, the columns can be constructed out-of-plumb (leaning) by that much. The vertical loads acting on this non-vertical structure induce additional moments into the structure, similar to P-D.
Member Out-of-Straightness is a result of the milling and manufacturing processes. Individual members are not exactly straight. The vertical loads acting on this non-straight member induce additional moments into the member, similar to P-d.
Residual Stresses are a result of the milling process. As a newly-rolled member cools, it cools unevenly. This results in localized stresses in the member, even in its unloaded state.
The Direct Analysis Method of AISC 360-05 requires that each of these effects be considered in the analysis of the structure, and gives acceptable means of doing so. Note that other valid methods that correctly capture these effects are acceptable in lieu of the methods explicitly given in AISC 360.
P-D and P-d effects can be determined using a second-order analysis. There are a number of different approaches for performing this analysis. In lieu of that, a simplified approach called the amplified first-order analysis can be used. This involves the calculation of B1 (for P-d) and B2 (for P-D), by which the design forces are amplified.
The effects of structure out-of-plumbness can be included in the analysis by directly modeling the structure with the out-of-plumb geometry. Alternatively (and more practically), horizontal notional loads equal to 1/500 of the vertical gravity loads can be applied to the structure. Notional loads are merely a portion of the gravity loads applied horizontally.
The effects on the structural stiffness of member out-of-straightness and residual stresses can be accounted for by using a reduced bending stiffness EI* equal to 0.8tb times the nominal stiffness EI, and a reduced axial stiffness EA* equal to 0.8 times the nominal axial stiffness EA.
Note that the effects on the individual member strength of member out-of-straightness and residual stresses are handled directly by the column strength formulas in Chapter E.
These stability effects are neither new nor peculiar to AISC 360-05. They potentially influence all structures regardless of the code used to design the members. Some codes may handle these effects explicitly; otherwise they need to somehow be accounted for. With the explicit analytical requirements, AISC 360-05 has made the consideration of these effects more transparent.
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The Structural Team in the industry
ACI Fellows Shri Bhide, Rita Oglesby, and ACI Member Allan Bommer represented Bentley at the American Concrete Institute Fall Convention in Saint Louis in early November. Bentley is enthusiastically involved in all areas of ACI activity from development of the ACI 318 building code to the creation of software interoperability standards for concrete structures.
At the convention, Shri Bhide presented “Fire Resistant Design of Concrete Bridges,” and Allan Bommer presented “Building Information Modeling (BIM): Issues and Obstacles” and “Assumptions in FE Slab Analysis and Their Design Implications,” all popular sessions. In addition, Allan Bommer co-moderated two sessions on “Practical Use of Finite Element Analysis in the Design of Concrete Structures.” As well, Shri and Allan enjoyed some face time with Bentley product users during informal Q and A sessions.
Between Shri, Rita, and Allan, Bentley is represented by voting/associate members of ACI Committees 118 Use of Computers, 318D Axial and Flexure, 342 Evaluation of Concretes and Bridge Elements, 343 Concrete Bridge Design, 348 Structural Safety, 365 Service Life Prediction, 421 Slabs, 423 Prestress, 435 Deflections, 447 Finite Element Analysis, and ACI Young Member Award for Professional Achievement. Rita is also involved in planning the ACI spring 2011 convention in Tampa.
The next ACI convention will be held in San Antonio in March 2009, where Bentley will once again be instrumental to its success.
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Structural Quiz
Last time we asked you the following question:
Into a regular glass tank, eight small steel balls are placed. Then the tank is filled with water so that the top of the water is level with the very top of the eight steel balls. The eight balls are removed and replaced with one larger steel ball (into the same tank with the same water, none is lost).
The larger steel ball is submerged in the water to exactly half of its diameter.
Which is true:
a.) The larger steel ball is exactly twice the diameter of the smaller ones.
b.) The diameter of the larger steel ball is less than twice the diameter of the smaller ones.
c.) The diameter of the larger steel ball is greater than twice that of the smaller ones.
d.) Cannot be determined.
Volume of Sphere = 4/3( Pi) r3
Pi = 3.141592653589793 (approx)
The correct answer was b.)! 184 people took part in the challenge, and12.5 percent of you got it right this time. Correct answers were submitted by:
- G. Doley, Worley Parsons
- Dan Black, Nolen Frisa Assoc.
- J Bowen, Hatch
- Arif Mahmood, Tadjer-Cohen-Edelson Associates
- Guillermo Guerrero, KBR
- Saddiq S Peerzada, Grip
- Daniel Dittrich, Intecha, spol. s r.o.
- Sean Morris, Coreslab Structures
- Doug Henderson, KlingStubbins
- Kevin Guillotte, Simpson, Gumpertz, & Heger Inc.
- Dan Donnachie, CVM Engineers
- Simon Beckwith, BDP
- Eric, Turbine Air Systems
- Andrej Zabrodsky, visia
- Deepak Kulkarni, DEEPAK KULKARNI CONSULTANTS
- Merlijn Kamps, VSH United Steel Company
New challenge - this one is a structural challenge again!
Which of the following moment diagrams is correct for a cantilever column subjected to a high axial load and a shear (consider 2nd order elastic effects)?
Submit your answer here!
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Be Communities
One of the main goals in the structural group is to solicit feedback from our customers as well as simultaneously informing them of the latest features, releases, bugs, and “How To” tutorials. We also like to engage with our strong customer base. A forum for all of the above is Be Communites, where we maintain several blogs as well as wiki-based documentation, forums, and other resources.
Have a look for yourself and learn more about: RAM Structural System, RAM sBeam, RAM Advanse, RAM Connection, STAAD V8i, and many more.
Click through to these structural blogs:
We encourage you to join Be Communities, where the world’s infrastructure communities come together to connect, communicate, and learn from each other.
Until next time!
The Bentley Structural Team
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