How do structural consultants save time and effort in every project stage?

Did you know that inadequate planning in the early stages of a structural project can lead to costly rework and delays? I have seen firsthand how meticulous planning at each project stage can save time and resources. In this article, we’ll explore how you can support clients—from developers to architectural consultants—throughout each critical stage, starting with the often-overlooked concept stage.

Main Project Stages:

a. Concept Stage.

b. Schematic Stage.

c. Detail Design Stage.

d. Tender Stage.

e. Issue for Construction (IFC) Stage.

Note: Municipality & Authority Approval are not mentioned here as the structural role differs from country to country.

a-Concept Stage:

The concept stage is crucial, yet often overlooked by many consultants.

We believe that investing effort in this phase saves time and resources, making subsequent stages more straightforward.

Key Points in the Concept Stage:

1-. Understand Client Requirements: Collect all available information from the client to fully grasp their needs and requirements. Ensure the client is aware of all necessary documents required to proceed smoothly, avoiding any interruptions in the workflow.

2. Propose Multiple Options: Present several structural system options, highlighting the pros and cons of each. Ensure the client fully understands and agrees with the chosen system. This agreement helps to eliminate the possibility of changes in later stages under the guise of cost reduction or due to input from other stakeholders.

3. Budget Considerations: Determine the construction budget for the structural work early in the project. This budget serves as a guideline for coordinating with the architectural team and selecting the appropriate structural system within the client’s financial constraints. For example, in one of our projects, a client requested a 25-meter clear span for an office building. We proposed several options to meet this requirement but, understanding the client's budget constraints, highlighted the construction cost implications. This transparency allowed the client to make an informed decision, ultimately opting to reduce the span to 15 meters, which still met the functional requirements within their budget.

Monitoring the client's budget and comparing it to the design at each project stage is crucial to avoid any rework. In several instances, projects were completed and later sent to us to study how we could reduce costs.

4. Agree on Design Criteria: Establish design criteria, materials, design codes, and any special client requirements. Ensure a thorough understanding of local building codes, as they often take precedence over international codes. For example, Design Coefficients and Factors for Seismic Force-Resisting Systems in the SBC local code may differ from those in the ASCE code.

5. Basic Analysis: Conduct preliminary analyses to demonstrate the recommended systems without delving into detailed calculations. Use your experience to minimize effort.

6. Initial Coordination with Geotechnical and Wind Tunnel Consultants: Provide proposed borehole locations and depths. Supply basic structural dynamic behaviour information to wind tunnel teams for preliminary analysis.

7. Highlight Potential Cost Reductions or Construction Challenges: Identify potential savings and construction challenges early in the project. Communicate these insights to the architectural team and the client to ensure cost efficiencies are realized without impacting the building’s function.

b-Schematic Stage

After agreeing on the structural layout with the client, the schematic stage involves developing analysis models and coordinating with other disciplines. The challenge here is to accommodate all disciplines' requirements while finalizing concrete dimensions. This stage includes several meetings with wind tunnel teams, geotechnical consultants, MEP, landscape, and other consultants to refine the structural system and determine the most efficient structure. At the end of this stage, refine your construction budget analysis and ensure it remains within the client’s budget.

c-Detail Design Stage

During the detail design stage, the focus shifts to developing detailed drawings with reinforcement details to ensure the contract package is ready for pricing. This phase involves minimal coordination with other disciplines, allowing for concentrated effort on the structural details. The project cost should be finalized at this stage and should remain within the client’s budget.

d-Tender Stage

In the tender stage, contractors will price the package, and you may receive queries regarding the design. Respond to their queries and add the required details to ensure clarity in the IFC package.

e-Issue for Construction (IFC) Stage

At this stage, a complete structural package is prepared, incorporating any additional contractor requirements.

By meticulously supporting your clients through each project stage, you help them achieve their goals efficiently and effectively and this is our proactive approach in our office, especially in the concept stage, sets the foundation for successful project execution and minimal rework.

Conclusion

Understanding the importance of each project stage and the role of a structural consultant can save time, reduce costs, and ensure the success of the project. Our detailed attention to the concept stage and continuous support throughout the project lifecycle distinguishes our consultancy services. Thoughtful planning and expert guidance can make a significant difference in achieving project goals smoothly and efficiently.

 Our commitment to client support extends beyond the submission of the IFC package, as we respond to any site team queries to ensure the project is completed as designed.

By meticulously supporting our clients through each project stage, we help them achieve their goals efficiently and effectively. Our proactive approach, especially in the concept stage, sets the foundation for successful project execution and minimal rework.

Minimum reinforcement ratio in piles

1-Introduction :

The Piles are a structural element that can be wood, steel sections, precast concrete, cast-in-place concrete, and composite type piles and etc.

The main function of the piles include :

1- Transferring load from the superstructure through weak compressible strata onto stiffer soils or onto rock.

2-Resisting uplift force when used to support tall structures or basement below the groundwater table.

3- Control the settlement.

4- Used in marine structures to resist the lateral loads from the impact of berthing ships and from waves.

2- Type of piles based on function.

Classification of piles with respect to functional behaviour as follows :

a- End-bearing pile: This type of pile derives most of its capacity from a bearing stratum on which the tip bears.

b- Friction pile: This type of pile derives its resistance primarily from friction or adhesion along the length of the pile. They are commonly used where a bearing stratum is too deep to be usable. A pile that resists tension does so by friction and would be considered a friction pile.

c- Combined end-bearing and friction pile: This type of pile derives its resistance from a combination of end bearing and friction

d- Batter pile: this is a pile that driven at an angle with respect to vertical to resist horizontal force.

e-Mirco pile.

2- Pile reinforcement detail :

Pile reinforcement detail is one of the issues that are unclear, and there is conflicting information in ACI 318, ASCE 7 and IBC foundations, but now ACI 318-19 eliminated that conflict. Below table explains the minimum reinforcement requirements.

References.

1.   Building code requirements for structural concrete (ACI 318-19) and commentary.

2.   International building code 2015

3.   Foundation analysis and design.

Introduction to Diaphragm design.

1-Diaphragms:

Diaphragms is a horizontal or sloped system acting to transmit lateral forces to vertical elements of the lateral force-resisting system (LFRS). Generally provided by the floor and roof systems of the building; sometimes, however, horizontal bracing systems independent of the roof or floor structure serve as diaphragms.

There are many types of materials and systems for use as floor and roof diaphragms.

Such as; Concrete slabs, Precast concrete floor planks with concrete topping, Metal decking with concrete fill, Roof sheathing .. etc.

2- Diaphragms roles for the structure, the main purpose of the diaphragm is to distribute lateral forces to the elements of the LFRS also it is doing the following:

1- Resist gravity loads.

2-Provide lateral Support to vertical elements.

3-Transfer lateral inertial forces to vertical elements of the seismic force-resisting system.

4- Transfer forces through the diaphragm.

The Largest diaphragm transfer forces should be anticipated at offsets or discontinuities of the vertical elements of the seismic-force-resisting system such as.

(a) Setback in the building profile

(b) Podium level at grade.

3- Diaphragms components:

A-Chord:

Is assumed to resist all the flexural tension from the diaphragm in-plane bending moment resulting from the lateral load. In case the edge beam is not existed the slab will act as a deep beam to resist flexural tension force and the chord tension reinforcement to be placed within h/4 of the tension face, where h is the diaphragm width in the direction of the analysis (section 12.5.2.3 of ACI code).

B-Collector:

Also called drag struts or ties, are diaphragm framing members that collect diaphragm shear forces from laterally unsupported areas to vertical resisting elements. The collector width can be fit within the shear wall width but in some cases, it has to be wider.

SEAOC 2005 recommends the collector effective width beff to not exceed the wall width plus a width on either side of the wall equal to half the contact length between the diaphragm and the wall.

4- Behavior of Diaphragms

The behavior of a diaphragm can be as beam that is supported springing which represents the lateral stiffness of lateral resisting elements. The floor or roof system acts as the beam web which resists the design shear force the chords behave as flange elements resisting the axial tension or compression resulting from flexural behavior.

5-Type of diaphragms:

Diaphragms are typically classified into three categories: rigid, flexible and semi-rigid

a- Rigid diaphragms 

ASCE7-10 ( section 12.3.1.2) permits the assumption of rigid if the diaphragms aspect ratio is 3 or less for seismic and 2 or less for wind load ( section 27.5.4 of ASCE7-10) if the structure has no significant horizontal irregularities. The seismic story shear is to be distributed to the vertical elements of the LFRS based on the relative lateral stiffness of those elements.

b-Flexible:

Diaphragms is permitted to be flexible when the computed maximum in-plane deflection of the diaphragm under lateral load is more than two times the average story drift of adjoining vertical elements of the seismic force-resisting system of the associated story under equivalent tributary lateral load as shown in the above Fig. 12.3-1.

The seismic story shear is to be distributed to the vertical elements of the LFRS based on the tributary area. And the diaphragm deflection is significantly high compare to LFRS

c- Semi-rigid diaphragms simulate actual in-plane stiffness properties and behavior. it should be modeled when significant in-plane deformation does occur, or when required by code.

6- Code requirements:

The seismic design of the diaphragm is required for all buildings in SDC B to F.

ASCE7-10 12.10 required diaphragms to be designed for the internal forces determined as the maximum of :

a-    

b-    

The detailing of diaphragms is generally independent of the type of LFRS for building, therefore, the R-value does not appear in the upper and lower limit equation.

Section 18.12 of ACI 318-14 shall only apply for diaphragm design in building assigned to SDC D to F only. while chapter 12 of ACI318-14 provisions shall be applied and for buildings assigned to SDC B and C.

7- Diaphragm modeling and analysis approaches

The internal force in diaphragm can be calculated from hand calculation till complex computer analysis depending on the building's irregularity.

The following methods can be used for analysis:

1-    Equivalent beam model.

2-    Equivalent beam on spring model.

3-    Corrected equivalent beam model.

4-    Strut and tie model.

5-    Finite element model.

8-How to obtain the diaphragm in ETAB.

The diaphragm forces can be obtained through sections cut as illustrated in the following link:  https://wiki.csiamerica.com/display/etabs/Diaphragm+forces

Bear in mind the Stiffness modifiers for RC diaphragms commonly fall in the range of 0.15 to 0.50 when analyzing the building for design-level earthquake demands (Nakaki, 2000).

References.

1.   Building code requirements for structural concrete (ACI 318-14) and commentary.

2.   Minimum design loads for buildings and other structures (ASCE 7-10)

3.   NEHRP Seismic Design Technical Brief No. 3.