AMECO-17 CASE STUDY
La Laurentienne
Office Tower

Project: La Laurentienne Office Tower
Spec's: 27 storeys, concrete
Location: Montreal, Canada
Developers: Marathon Realty & Lavalin
Structural Engineer:
Rand Engineering Corporation,
Mississauga, Ontario, Canada
Software: AMECO-17

Challenge:
Traditional Design, Traditional Problems
The developers were finalizing the design of a new $65 million, 27-storey reinforced concrete office tower in downtown Montreal. Initial design of the tower started the traditional way, which resulted in many of the traditional problems: the complexity of the geometry, time constraints and proposed changes to optimize prompted the developers to seek alternate solutions. Having heard that RAND Engineering Corporation was using AMECO-17, a program that specialized in the design of high-rise buildings, they elected to engage RAND's services to complete the project.

RAND was faced with the chal enge of integrating a modified structural design with the architectural and engineering work previously completed ­ and to do this, of course, in the most timely and cost-efficient manner possible. Special efforts had to be made to minimize the impact on curtain wal and mechanical systems, al the while keeping in mind architectural requirements, building layout and height constraints. A number of different designs were to be produced to minimize major modifications, or revisions, to the building concept already
developed.

A typical floor framing (hexagonal shape) of the 27-level building consisted of (a) flat slabs with drop panels, (b) beams on the perimeter of the floor and (c) shear walls around the service area. The ductile rigid frame on the perimeter, and the shear walls at the centre would thus resist the seismic and wind forces.

The structure had to be designed for gravity dead and live loads and seismic and wind forces in accordance with the National Building Code of Canada.

Solution:
Design Optimization

To minimize structural costs, RAND needed to evaluate several framing schemes--and fast! By conventional methods, an optimization of such a magnitude, along with its effect on the design and construction process, would have taken too long to develop. But by using AMECO-17, time was on RAND's side.

Scheme A First, the original concept of the building had to be structurally designed with the help of AMECO-17. At each floor, the framing had four 40' long shear walls in the Y-direction and eight 8' long shear walls in the X- direction (see Fig. 2). Ameco-17 projected this concept would come in at nearly $13 million in construction costs (see Fig. 3)

Result: Better, Stronger, Easier, Faster
AMECO-17 produced a design with the slab thickness reduced from 9" to 8", and the beam depths decreased from 30" / 24" to 18". This had the effect of further increasing the flexibility of the structure in both directions, and reducing seismic forces by 30%. As a result, construction costs were reduced to $11,773,265 (see Fig. 5), a savings of $1,130,117 over the original concept. The adoption of Scheme C had additional benefits as well:

1) Faster construction time (simplified core)
2) Eliminated footings for removed walls
3) Simplified construction procedures: flying forms
could be used because of reduced beam depth

Rand was able to run the three optimization schemes and produce the final design documents, complete with reinforcing schedules, lists of materials and their associated costs, in just 20 days, start to finish.

AMECO-17 allowed the engineering design time to be substantially reduced from the usual 600 man-hours to only 35 man-hours. And 15 of the 35 hours were spent by RAND engineers in meetings with the client to interpret and explain the design results. That meant that AMECO-17 had done the job 17 times faster, and in 96% less time.

It took just 6 hours for a RAND engineer to input the necessary commands in AMECO-17 to design the tower, despite it being composed of 3,537 members. (See Fig. 6) That's because with AMECO-17, member sizes did not have to be given, loads did not have to be manually calculated, nor did any load cases or combinations have to be specified. Only concrete strength, loading parameters and member connectivities were inputted, as well as minimum dimensions for some members. Once these inputs were done, AMECO-17 required just a few additional instructions to produce the other two design schemes.

Based on these input commands, AMECO-17 generated the geometry of the structure in 3-D, calculated the floor dead and live loads on each slab and beam, calculated the seismic forces, set up loading cases, and through a continual cyclical process, designed the whole structure faster than traditional methods or other structural engineering software.The little time it took AMECO-17 to generate the alternative schemes gave Marathon, Lavalin and the RAND team ample time to discuss specific criteria and familiarize themselves with details of the design process.