ANALYSIS & DESIGN of SUPERSTRUCTURE Combined with Foundation (TowerPeak)

Analysis and Design of Superstructure Combined with Foundation(TowerPeak)

Analysis and design of
superstructure combined
with foundation

Full name of this software is “ANALYSIS AND DESIGN OF SUPERSTRUCTURE COMBINED WITH FOUNDATION” (or TowerPeak in short). It is developed by “C & J Software Design Co., Ltd. ” as specialized software for the building industry to perform structural analysis and design. The Ministry of Housing and Urban-Rural Development of PRC (People’s Republic of China) has granted it an assessment certificate in December 2012. (Their relevant reference number is [2012, #139]). The level being classified is as “Advanced World Level”. Please note in particular that TowerPeak adopts all relevant current PRC’s design codes and technical standards. Read more... TowerPeak has also obtained approval and certification from Hong Kong Department (Reg No. S0715 & S0731).Other design codes for USA, Europe and Australia are also used in the TowerPeak.It is well recognized that separation of superstructure & foundation (in structural analysis) is an “inevitable” compromising way to simplify the complex process of full building analysis. Doing so is far from ideal and may have certain serious (although not obvious) drawbacks. For instances, the “true” factor of safety at certain areas of the structure may be insufficient, whereas in some other areas the structure may be grossly excessive (thus uneconomical). Even though there is no reported case of building collapse to date, it is a significant issue. One clear evidence which indicates re-distribution of stress, can be revealed from the numerous cases of concretebuilding cracks (especial on those lower floors closer to foundation) soon after completion. This effect will not only shorten the usable life of a building but will also greater increase the cost of building maintenance and repair. Such “defective” design approach should and will be abandoned sooner or later. It is only a question of time. Having said the above, the path to have a practical way to do integrated structural analysis & design on superstructure coupling with its foundation, is a very difficult task. Especially, it has to achieve the accuracy and efficiency required in practice. Through unremitting efforts of our team, such comprehensive software is now made with the name of “TowerPeak”, for which the profession of structural engineering has already been waited a long time. Its high practical value will achieve high accuracy and quick speed analysis for numerous high rise buildings to be designed in future. In addition, using it will avoid unsafe structural element design on one hand and achieve economical use of building material & effort on the other. Going along with TowerPeak is a powerful interface program named “Proform”, which is specifically developed by us to provide a real “what you see is what you get” platform for the User. Instead of printing out, all computational data can be stored in a CD or DVD while displaying on screen. It can save huge amount of printing time, effort & paper plus makes retrieval of information much easier.

 

Foundation Structure

“TowerPeak” incorporates all foundations (including piled foundation and footing), ground beams, pile caps and piles as individual elements to perform a single foundation structural analysis. Every node of elements will be taken to have 6 degrees of freedom of analysis. For line elements (such as ground beams, piles and tie beam between footings), the analysis will be based on classified structural mechanic method. For footings and pile caps, finite element method will be utilized, with these elements being taken as either “thin-or-thick” plate elements. Doing structural modeling & analysis in such a way, results of high precision and consistency can be expected to be obtained efficiently. Read more... It is no longer required to make specific structural simplifications or assumptions to specific type of foundations. In addition, localized effects can properly be accounted for. With the aid of AutoCad (a popular drawing software), any geometrical shapes can be inputted into TowerPeak. This feature is useful for input information such as cross-section of elements (such as slabs, beams, columns, walls and etc).or as load patterns (such as area or point load) acting on slab element. Actually, graphical information can be transferred (import or export) between TowerPeak and AutoCad. As a result, under the setting of AutoCad, TowerPeakcan generate graphical output (or results) such as 2-D plan, 3-D plan, beam & column schedule drawing, Rebar drawing and many others. The core portion of “TowerPeak” is developed from our company’s earlier software, named “Foundation Design on Elastic Cap” (FDE). As a result, “TowerPeak” can be viewed as an enhanced version of FDE. However, with our significant technology breakthrough, the areas of application are much extended. Now, all foundation elements for a building structure can be taken as a space 3D framework connecting by tie beams. Footings are no longer be required to be at 1 single level. Those tie beams which connect footings together, can be taken as sloping. However, individual footings and pile caps are still required to be leveled. To avoid the unnecessary complexity of taking piles as part of the space framework, piles are regarded as sub-structures. Rigidity of pile will be calculated through lumping from pile tip toward pile head. (Note: soil springs are initially distributed along pile length plus an equivalent axial support). After the lumping process, an equivalent rigidity matrix corresponding to the pile’s rigidity along the 6 degrees of freedom at the node of pile head can then be calculated. Modeling the foundation structural system in such a way, the apparent “infinity” system can be reduced to a manageable size for speedy and high precision analysis. Calculation of the equivalent pile axially rigidity at pile head is to be carried out by our earlier software named<>, (PSA), which principal usage is to compute settlement of single pile and/or pile group. Calculation of the equivalent pile lateral rigidity at pile head is to be carried out by our earlier software named <>, (ESB), which principal usage is to analyze combined footing as continuous beam having elastic supports In short, the main features of “TowerPeak” can be summarized as follows:- 1. “TowerPeak” adopts space modeling. Individual footings and/or pile caps are modeled as plate elements having multi-sides. Ground beams and tie beams are modeled as line elements. They are then analyzed by Finite Element Method a space 3D setting. With the exception that individual footing or pile cap has to be leveled, there is no other specific structural simplifications or assumptions to be required in the current version of TowerPeak. (This restriction is expected to be removed in near future revision). It is worthwhile to note that TowerPeak have features to handle footing with penetrations or with varying thickness. For static structural analysis only, TowerPeak can consider the possible situation that raft foundation being slide against its supporting surgrade or piles being dislodged from their pile cap. The analysis will be based on friction simulation through iteration process. 2. The programming procedure for “TowerPeak” is ground breaking. It utilizes the advantage multi-tasking and multi-threading (by using a number of sub-programs simultaneously). As a result, full potential capacity of nowadays PC’s powerful CPU is being made use to increase computation speed. VIII. Other important features, which “TowerPeak” processes, include the followings: 1 To do meshing (for finite element method) for the whole building structure automatically. No additional manual adjustment is required, 2 To extract relevant results automatically. For example, critical values can be extracted and them outputted (and displayed) overlaying on floor plan for easy interpretation by User, 3. To assign arbitrary shape of cross-section of any members, members can be made of different construction materials (such as structural steel section or reinforced concrete), 4. To do Re-bar design for any of the abovementioned cross-sections, 5. To adjust sizing of ground beams and tie beams after completion of analysis on load case combination, 6. To work out Bill of Quantities quickly and accurately, 7. To achieve foundation design automation, without minimal supervision by structural engineer. Lastly, “TowerPeak” (i.e. the foundation module) has successfully obtained approval and certification from Hong Kong Buildings Department, Hong Kong SAR Government. The registration no. is S0627.

Superstructure & Foundation
integrated analysis & design
(TowerPeak)

Doing structural analysis & design for Superstructure and Foundation separately and independently is the traditional (but inadequate) practice for building design. The resulting building structure is “unreliable” in many aspects. For example, the actual natural frequency may be several times higher than the assumed one. Effects due to temperature difference may also be several times severe than expected. In order to tackle these problems, we have developed a ground breaking Software which is able to combine Superstructure with Foundation for both static and dynamic structural analysis.Read more...If only in static analysis, TowerPeak also takes into account the contact between the raft foundation and pile foundation and foundation platform and disengagement between the problem, between raft foundation and foundation were simulated friction, these are used repeated approximation calculation method. To carry out dynamic structural analysis for earthquake design, Foundation system can be incorporated in the whole building structure as one single system. The discussion on lumped mass at relevant nodal points for the superstructure can be referred to Part I. For the foundation elements, the relevant nodal points for lumped mass are at the intersection points between (footing/column, wall, tie beam or pile). The mass at other nodal points will then be lumped to these relevant node points. Please refer to the relevant section of the Part I for more details. When considering construction phasing design, the foundation itself plus the level 1 of the Superstructure should be taken as the stage “1”. Please refer to the relevant section of the Part I for more details. The operation is firstly, establishing models for Superstructure (data file with extension SSD & MSD) and Foundation (data file with extension IFD & GFD) respectively. Subsequently, use file “SFD” to create a combined model. An integrated analysis can then be carried out on the combined model. Lastly, “TowerPeak” (Superstructure with Foundation combined) has successfully obtained approval and certification from Hong Kong Buildings Department, Hong Kong SAR Government. The registration number are S0715 (Analysis Module) &S0731 (Design Module) respectively.

SPECIAL FEATURES

of TowerPeak

HIGH PRECISION

The principal technique of “TowerPeak” is to utilize the structural stiffness of every floor sub-system as an entity for analysis. The intermediate analyzed results will then be “re-inputted” into the full building global analysis to calculate another sets of intermediate displacement and internal force.

ADOPTS SPACE MODELING

"TowerPeak" adopts space modeling. It is achieved by modeling floor slab & wall as shell elements with multi-sides and beam & column as line elements.  The shell & line elements will then be analyze in a space setting. With the exceptions that slab has to be horizontal and wall has to be vertical, "TowerPeak" does not need to work with other structural simplifications or unusual assumptions.

ADDED ADVANTAGE

An add advantage of "TowerPeak" is for underground basement. The basement of a building can be simplified by inputted as part of the global building structure. It makes data input and output interpretation much more direct and easy.

 

 

 

 

 

PROGRAM COMPUTING SPEED

Thanks to the technology breakthrough, computation speed can be kept even with the high precision being achieved.

TIME CONSUMING

Reduction of design effort and time significantly. Thus, both cost & timeframe to complete a building structural design can be greatly reduced.

OBTAINED APPROVAL

"TowerPeak"(i.e. the superstructure module) has successfully obtained approval and certification from Hong Kong Buildings Department, (Reg.No.S0715 & S0731) and P.R. China(2012,#139).

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