This guide dives into the nitty-gritty of AESS steel, covering everything from its various categories to key aspects to consider when using it. Readers will gain insights into the specifications that set AESS apart, learn about the importance of precise welds, and understand the careful handling required. The article also explores the crucial role of shop drawings in AESS projects and how this material fits into the broader landscape of structural steel. Whether you’re a seasoned pro or new to the field, this comprehensive look at AESS Steel aims to boost your knowledge and skills in this exciting area of construction.

In the world of construction, AESS steel has become a game-changer for architects and engineers alike. This innovative material combines the strength of structural steel with a sleek, aesthetically pleasing finish, opening up new possibilities in design and functionality. AESS steel has an impact on how buildings are conceptualized, constructed, and perceived, making it a hot topic in the industry today.

Understanding AESS Categories

Architecturally Exposed Structural Steel (AESS) has revolutionized the way buildings are designed and constructed. To ensure clarity and consistency in AESS projects, a categorization system has been developed. This system helps architects, engineers, and fabricators to communicate effectively and achieve the desired aesthetic and functional results. Let’s explore the five categories of AESS:

AESS 1: Basic Elements

AESS 1 serves as the foundation for all other categories and represents the minimum treatment of exposed steel beyond standard fabrication. This category is suitable for basic elements that require enhanced workmanship. AESS 1 is the default specification for structural steel that will be visible.

Key characteristics of AESS 1 include:

1. Surface preparation to SSPC SP-6 commercial blast cleaning standard.
2. Sharp edges ground smooth.
3. Continuous weld appearance.
4. Standard structural bolts with consistent head orientation.
5. Weld splatters removed.

The cost premium for AESS 1 typically ranges from 20% to 60% over standard structural steel. This category is often used in roof trusses for arenas, warehouses, big box stores, and canopies.

AESS 2: Feature Elements Not in Close View

AESS 2 builds upon the characteristics of AESS 1 and is appropriate for elements that will be viewed from more than 20 feet away. This category serves a level of fabrication and erection specific to structural steel elements viewed from a distance.

Additional requirements for AESS 2 include:

1. Fabrication tolerances for straightness are half that of standard requirements.
2. Fabrication marks are not visible.
3. Welds are uniform and smooth but may be visible.
4. Greater consistency in the welding process.

The cost range for AESS 2 is typically higher than AESS 1 due to the additional requirements.

AESS 3: Feature Elements in Close View

AESS 3 is ideal for elements that can be viewed closely within 20 feet or that are within a person’s reach. This category includes all the requirements for AESS 1 and 2, along with more specific attention to detail.

Key characteristics of AESS 3 include:

1. Mill marks removed.
2. Butt and plug welds ground smooth and filled.
3. HSS weld seams oriented for reduced visibility.
4. Cross-sectional abutting surfaces aligned.
5. Joint gap tolerances minimized.

The cost premium for AESS 3 could range from 60% to 150% over standard structural steel, depending on the complexity and level of final finish desired.

AESS 4: Showcase Elements

AESS 4 represents the highest standard of quality expectations for AESS products. This category is used where the designer intends the form to be the only feature showing in an element.

Key characteristics of AESS 4 include:

1. All welds are ground and filled.
2. Edges ground square and true.
3. All surfaces sanded and filled.
4. Tolerances are more stringent, generally to half of the standard tolerance.
5. “Glove” smooth surfaces.

The cost premium for AESS 4 elements could range from 100% to 250% over standard structural steel. This category is often used in high-profile projects where the sculptural nature of steel is meant to be the main focus.

AESS C: Custom Elements

AESS C allows for flexibility in choosing characteristics that deviate from the requirements of AESS 1, 2, 3, and 4. This category provides designers with greater freedom and notifies fabricators and erectors of noteworthy differences from typical category requirements.

To better understand the differences between AESS categories, consider the following table:

Characteristic	AESS 1	AESS 2	AESS 3	AESS 4
Viewing Distance	Any	>20 ft	≤20 ft	Close range
Surface Preparation	SSPC SP-6	SSPC SP-6	SSPC SP-6	SSPC SP-6
Sharp Edges	Ground smooth	Ground smooth	Ground smooth	Ground smooth
Weld Appearance	Continuous	Uniform and smooth	Uniform and smooth	Ground and filled
Bolt Heads	Consistent orientation	Consistent orientation	Minimized gaps	Often welded
Mill Marks	Visible	Not apparent	Removed	Removed
Tolerances	Standard	Half standard	Tighter	Most stringent
Cost Premium	20-60%	Higher than AESS 1	60-150%	100-250%

Understanding these AESS categories helps in selecting the appropriate level of finish for a project, and balancing aesthetic requirements with budget constraints. Each category builds upon the previous one, offering increasing levels of refinement and attention to detail. By carefully considering the viewing distance, project requirements, and budget, architects and engineers can specify the most suitable AESS category for their structural steel elements.

Key Considerations for AESS Implementation

When implementing Architecturally Exposed Structural Steel (AESS), several key factors need to be carefully considered to achieve the desired aesthetic and functional results. These considerations help architects, engineers, and fabricators communicate effectively and make informed decisions throughout the project.

Member Visibility

The visibility of AESS members plays a crucial role in determining the level of finish required. If a steel element is not readily visible, there’s no need to identify it as AESS. In some cases, only one side of an exposed steel column or braced frame may be visible, while the other side is blocked by a wall or another component. In such situations, it’s possible to specify a specific AESS category only for the visible side of the member.

Viewing Distance

The distance from which AESS elements will be viewed has a significant impact on the level of fabrication and erection required. Details tend to become less noticeable as the viewing distance increases. The AESS category system recognizes this fact and uses a 20-foot viewing distance as a critical threshold to separate categories AESS 2 and AESS 3.

1. AESS 2: Appropriate for elements viewed from more than 20 feet away
2. AESS 3: Ideal for elements viewed within 20 feet or within reach

When objects are beyond 20 feet, the distinction between components becomes less clear to the naked eye. At distances of 100 feet or more, the level of visible detail diminishes even further.

Location and Lighting

The location of AESS elements, whether interior or exterior, has a significant impact on the type of coatings and protections required. Exterior AESS must withstand more corrosive or harsh climate conditions, necessitating additional surface preparation and protective coatings to ensure longevity.

Lighting plays a crucial role in how AESS is perceived:

• Interior AESS: Lighting typically has the greatest impact
• Exterior AESS: Sight lines are the most important factor

In high ceilings with low lighting, details may not be as visible. However, brightly lit elements tend to expose more texture and surface blemishes. It’s essential to determine the location and type of lighting concerning AESS components before specifying the appropriate category.

Coatings and Style

The selection of coatings, such as paint or intumescent fire protection, should be coordinated with the location and lighting intent for AESS members. Glossy coats tend to reveal every imperfection and surface variation, requiring greater care and surface preparation. On the other hand, thicker intumescent coatings or matte finishes can help cover surface marks and blemishes, potentially reducing the need for certain surface preparation characteristics.

Two basic styles govern the design intent with AESS:

1. Tectonic: More expressive of details showcasing the steel assembly, often emphasizing bolted construction
2. Plastic: Uniform and smooth, using more welded or cast connections for a near-seamless appearance

The chosen design style is integral in determining the suitable AESS category based on the desired level of finish.

Adjacency

The relationship between AESS elements and other architectural components, such as windows, doors, and other signage, should be carefully considered. Proper placement and coordination can create a cohesive and visually appealing overall design.

By taking these key considerations into account, architects and engineers can specify the most appropriate AESS category for their structural steel elements, balancing aesthetic requirements with practical constraints. This approach ensures that the final result meets project expectations within budget and schedule while creating striking and durable architectural features that will stand the test of time.

AESS Fabrication and Installation Process

The fabrication and installation of Architecturally Exposed Structural Steel (AESS) requires meticulous attention to detail and specialized techniques to achieve the desired aesthetic and structural integrity. This process involves several crucial steps, each contributing to the final appearance and performance of the steel elements.

Special Handling Requirements

The fabrication of AESS demands exceptional care to maintain the steel’s pristine condition. Fabricators use nylon slings, chains with softeners, or wire ropes with softeners to handle the steel, minimizing the risk of marking or distorting the members. This careful approach extends to protecting any shop-applied paint or coating from damage during handling and transportation.

When temporary braces or fixtures are necessary for fabrication, shipment, or erection, special attention is given to avoid or repair any blemishes resulting from their use or removal. This level of care ensures that the final product meets the high aesthetic standards expected of AESS.

Surface Preparation

Surface preparation is a critical step in the AESS fabrication process, directly impacting the final appearance and durability of the steel. The level of preparation varies based on the AESS category and the intended finish. For AESS categories 1 through 4, fabricators typically clean the steel to meet the requirements of AS 1627 Sa2/Class 2 “Commercial Blast Cleaning”.

Before blast cleaning, several steps are taken:

1. Removal of grease or oil deposits using solvent cleaning (AS 1627 Part 1)
2. Elimination of weld spatter, slivers, and surface discontinuities
3. Softening of sharp edges resulting from flame cutting, grinding, and shearing

For steel that will remain unpainted, the AISC Code of Standard Practice requires cleaning with solvent cleaners to remove oil and grease, followed by sweeping with a fiber brush to remove dirt and foreign material. Steel destined for painting must be prepared to a minimum of SSPC-SP2 (Hand Tool Cleaning).

Welding and Grinding Techniques

Welding and grinding techniques play a crucial role in achieving the desired AESS finish. For categories AESS 1, 2, and 3, a smooth, uniform weld is generally acceptable. However, AESS 4 requires welds to be contoured and blended for a more refined appearance. Regardless of the category, all weld spatter must be avoided or removed where exposed to view.

Grinding is an essential part of the finishing process, particularly for high-end AESS applications. Effective grinding requires operators to apply the correct pressure at the appropriate angle, allowing the abrasive grains to remove metal efficiently without prematurely wearing the disc or burning out the tool. The optimal pressure for general industrial grinding applications typically draws between 8 and 10 amps.

For stainless steel and certain aluminum welds, a pull-lift-and-repeat method is often employed. This technique involves pulling the grinding disc over the weld seam, lifting, and repeating, which helps remove material more efficiently and minimizes the risk of bluing on the metal surface.

Erection Tolerances

AESS erection tolerances are crucial for achieving the desired aesthetic result. Unless otherwise specified, AESS members and components are plumbed, leveled, and aligned to tolerances equal to those permitted for structural steel. However, more stringent erection tolerances for AESS may require adjustable connections between adjoining structural elements, providing the erector with a means for adjustment.

Erectors must assemble the steel with careful planning and methods to avoid damage to the finished product. This often involves using specialized equipment and techniques to ensure precise placement and alignment of AESS elements.

By adhering to these specialized fabrication and installation processes, AESS projects can achieve the high-quality, visually striking results that architects and designers envision, while maintaining the structural integrity required for these exposed steel elements.

Conclusion

AESS steel has a significant impact on modern construction, blending structural strength with visual appeal. Its versatility allows architects and engineers to create striking designs that push the boundaries of what’s possible in building aesthetics. The categorization system for AESS provides a clear framework to communicate and implement different levels of finish, helping to balance visual requirements with practical constraints.

To wrap up, the successful use of AESS involves careful consideration of various factors, from visibility and viewing distance to fabrication techniques and installation processes. By understanding these aspects, professionals in the construction industry can harness the full potential of AESS to create buildings that are not just structurally sound, but also visually impressive. This approach to using steel as both a functional and aesthetic element continues to shape the future of architectural design.

FAQs

1. What does AESS stand for in construction?
Architecturally Exposed Structural Steel (AESS) refers to a type of steel that is specifically fabricated and finished to be used as a visible element in building designs, offering new aesthetic possibilities.

2. How do AESS 2 and AESS 3 differ?
AESS 2 requires uniform and smooth welds that appear consistent to the observer, though the welds need not be ground smooth. AESS 3, designated for feature elements in close view (within 6 meters), demands a higher standard of fabrication and erection, allowing for smooth but visible welds and some grind marks, with tighter tolerances compared to lower categories.

3. What are the specifications of the AESS 3 standard?
The AESS 3 standard is suitable for feature elements that are close enough (up to 6 meters away) to allow detailed observation. This standard permits the art of metalworking to be visible, including smooth welds and permissible grind marks, under stricter tolerances than usual.

4. Is it possible to galvanize AESS steel?
Yes, AESS steel can be galvanized. While not initially intended for aesthetic purposes, many architects now use batch hot-dip galvanized AESS to create artistic, durable, and sustainable elements with a modern, industrial look.

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