Frost Bank Center – Project Feature

Project Context: The Frost Bank Center

Sports arenas represent some of the most demanding building typologies faced by structural engineers. Their scale, geometry, and performance requirements push structural systems well beyond those encountered in conventional commercial buildings. The Frost Bank Center in San Antonio—home of the NBA’s San Antonio Spurs—offers a useful case study for examining these challenges, particularly at the interface between primary structure and building envelope systems.

As a major public assembly venue, the Frost Bank Center incorporates extensive exterior curtain wall systems that serve both architectural and functional roles. These systems must perform reliably under high wind loads, accommodate long-span structural behavior, and maintain serviceability despite significant building movement. Aquinas Engineering contributed to this project by performing the structural calculations for the exterior curtain wall anchorage system, supporting the safe and durable transfer of loads from the façade into the primary structural frame.

While often perceived as localized components, curtain wall anchorage systems in arena projects become critical structural elements whose performance is closely tied to the global behavior of the building. The Frost Bank Center illustrates how envelope-related structural engineering is integral to the success of large sports venues.

Exterior Curtain Wall Anchorage at Arena Scale

Curtain wall anchorage systems function as the primary load path between the façade and the building structure. In sports arenas, this role is amplified by the sheer scale of façade areas, the variability in support conditions, and the elevated performance demands imposed by both environmental loading and architectural intent.

At the Frost Bank Center, anchorage design required careful evaluation of wind-induced forces acting on large and often uninterrupted façade surfaces, as well as the mechanisms by which loads are transferred from curtain wall framing into structural steel or concrete backup. The geometry of the arena introduced further complexity, as irregular framing conditions and variable elevations influenced both anchorage layout and force distribution. Anchors, embeds, and connections had to be designed not only to satisfy code-prescribed strength requirements, but also to support constructability and long-term performance under repeated loading cycles typical of large public venues.

Serviceability proved equally critical to the performance of the curtain wall system. Long-span framing, cantilevered elements, and seating bowl geometry introduced deflections and inter-story drift beyond what is typically encountered in standard commercial buildings. Structural calculations for the Frost Bank Center’s curtain wall anchorage system accounted for differential movement between the primary structural frame and the façade, ensuring compatibility with glazing, sealants, and finishes. Tolerance management was also a key consideration, as the successful installation and performance of the curtain wall relied on alignment between structural movement assumptions and fabrication realities.

These considerations highlight a defining characteristic of arena projects: anchorage systems must be designed not only for strength, but explicitly for movement. Failure to do so can result in unintended load transfer, distress to façade components, and long-term durability issues.

Why Sports Arenas Present Unique Structural Challenges

Sports arenas differ fundamentally from typical building typologies in ways that directly affect envelope-related structural design. The combination of large occupant loads, long-span structural systems, and highly expressive architectural forms creates a structural environment where conventional assumptions often fall short.

Arenas are designed to accommodate tens of thousands of occupants, leading to significant gravity and lateral loading scenarios that vary depending on event type. Roof and concourse systems frequently rely on long spans and cantilevers, introducing global deflection, vibration, and redistribution effects that directly influence façade support conditions. Architectural emphasis on openness and transparency further elevates expectations for building envelope performance, placing additional demands on curtain wall systems and their supporting anchors.

In this context, envelope systems act less like secondary assemblies and more like extensions of the primary structure. Structural engineers involved in their design must therefore consider not only localized connection behavior, but also the broader structural response of the building as a whole.

Load Demands and Movement Behavior

Environmental loading plays an outsized role in arena design, particularly with respect to façade systems. Large and relatively uninterrupted exterior surfaces experience substantial wind pressures and suctions, which often govern anchorage forces. In regions with seismic design requirements, differential movement between floors and structural elements introduces additional complexity that must be captured in anchorage calculations.

Equally important is the structural movement that occurs under service-level loading. Gravity-induced deflections from long-span roof and concourse framing, lateral drift produced by wind or seismic events, and thermal movement across large building dimensions all contribute to relative displacement between the structure and the enclosure. Curtain wall anchorage systems must be capable of accommodating these movements while maintaining clear and predictable load paths. At the scale of a sports arena, even modest underestimation of movement can have significant implications for façade performance.

Geometry, Scale, and Their Impact on Envelope Systems

Arena architecture frequently departs from regular, orthogonal grids in favor of curved, sloped, and stepped forms. Seating bowl geometry, concourse transitions, and perimeter framing variations all influence how and where curtain wall systems connect to the structure.

From a structural standpoint, these conditions introduce non-repetitive anchorage details and variation in tributary areas and load magnitudes. The resulting increase in coordination effort requires close collaboration between structural and façade teams to ensure consistency in assumptions, detailing, and performance expectations. At arena scale, geometry becomes a governing factor in anchorage design rather than a secondary consideration.

Coordination Between Structural and Envelope Design

The Frost Bank Center reinforces a broader lesson common to arena projects: early and continuous coordination between disciplines is essential. Curtain wall anchorage design sits at the intersection of architectural intent, structural behavior, and fabrication constraints, and cannot be effectively addressed in isolation.

Successful outcomes depend on clear alignment between the structural engineer of record, specialty structural engineers, curtain wall designers, fabricators, and envelope consultants. When anchorage design is deferred or treated as a minor scope item, the risk of late-stage changes, constructability challenges, and performance deficiencies increases significantly. This risk is magnified on arena projects, where scale and complexity limit opportunities for correction once construction is underway.

Broader Lessons from the Frost Bank Center

The structural engineering effort associated with the exterior curtain wall anchorage system at the Frost Bank Center reflects several broader realities of sports arena design. Envelope systems must be treated as integral structural components rather than architectural accessories. The scale of arenas amplifies the consequences of small assumptions related to loads, movement, and tolerances. In many cases, serviceability criteria ultimately govern performance and durability more than strength alone.

These lessons extend beyond sports arenas to other large public venues and high-occupancy buildings where structural behavior and envelope performance are closely interconnected.

Conclusion: Advancing Knowledge Through Practice

Sports arenas offer structural engineers the opportunity—and responsibility—to engage with some of the profession’s most complex challenges. By examining real project conditions, such as those encountered at the Frost Bank Center, engineers can contribute practical insights that elevate industry standards and improve future outcomes.

At Aquinas Engineering, our work on arena-scale envelope systems reflects a commitment to rigorous structural analysis, interdisciplinary collaboration, and long-term performance. Sharing lessons learned from these projects allows the profession to advance its understanding of how structure and enclosure interact at the largest and most demanding scales.

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