Progressive Collapse Protection

STRUCTURAL TECHNOLOGIES brings to its clients bonded post-tensioning (P-T) technology that can be designed to provide reinforcement continuity and redundancy to resist the spread of damage and minimize the risk of progressive collapse.

VSL® Bonded, Post-Tensioned Floor Systems

As part of its full line of Force Protection solutions, STRUCTURAL TECHNOLOGIES brings to its clients bonded post-tensioning (P-T) technology that can be used to meet force protection and progressive collapse requirements in new construction.

STRUCTURAL TECHNOLOGIES can provide feasibility analysis, design assistance and cost development for a full range of P-T products and solutions to enhance force protection capabilities of existing structures as well as new construction applications.

Enhancing New Construction Designs Against Progressive Collapse

Post-tensioning systems may be designed to provide reinforcement continuity and redundancy to resist the spread of damage and minimize the risk of progressive collapse. Because the P-T tendons are bonded, they can fully re-develop the structural strength beyond the damaged location. The tendons can be profiled within the structural element to provide load reversal resistance that enhances the structure’s ability to withstand the loss of interior or exterior support, and create an “alternate path” for load resistance. Continuous and bonded VSLAB+® tendons placed in slabs can be used to provide the the necessary internal and peripheral tie forces to enhance a slabs ability to resist uplift and progressive collapse. The enhanced design provided by these bonded P-T systems are often required as part of creating the necessary “alternative path” performance for force protection applications.

Bonded Post-Tensioning

Advantages of Bonded P-T Tendons are:
  • Use of high strength strands improve a members ability to withstand a higher blast load
  • Bonded PT can maintain continuity and prestress force if an anchorage is lost
  • For beams and slabs, bonded tendons can be profiled to counter the internal forces resulting from a lost column and to resist moment reversals that can occur during a blast event


Bonded Post-Tensioning Systems

VSL multistrand PT systems consist of fully bonded prestressed strands contained in corrugated ducts. These systems can be used to provide continuous reinforcement in beams, columns and walls.

Bonded multistrand PT systems have been successfully applied to commercial buildings, healthcare and parking structure construction. Benefits include enhanced crack and deflection control and improved durability and resilience.

VSLAB+® Bonded Slab Systems

VSLAB+® Bonded Slab Systems

VSLAB+® bonded tendons consist of prestressed strands contained in low profile ducts that are fully bonded to the surrounding concrete and used to provide continuous reinforcement in slabs. The corrugated ducts are filled with a high-performance cementitious grout that encapsulates the strands and achieve full bond with the surrounding concrete. For aggressive environments, fully encapsulated anchorage systems and ducts are available. Intermediate anchorages systems are used to provide continuity of prestress at construction joints.

Design advantages include the ability to limit loss of capacity to localized areas when post tension tendons are cut, increased span lengths and improved load-carrying capacities.

Bonded Multistrand Systems

Bonded Multistrand Systems

A single multistrand tendon can hold up to fifty-five 0.5” or 0.6” strands encased in plastic or steel duct and is fully bonded using a high-performance grout. When bonded multistrand systems are used for large structural members such as beams and transfer girders, design advantages include increased span lengths and load-carrying capacity and reduced deflection. 



STRUCTURAL TECHNOLOGIES' force protection systems feature VSL® branded products - known worldwide as the products of choice for both new and repair post-tensioning applications. Structural Technologies, LLC is the exclusive licensee of VSL® Post-Tensioning Systems in the United States.

VSL® and VSLAB+® are the registered trademarks of VSL International Ltd.
Specialized Engineering Support Services

Assessment of Blast LoadsSTRUCTURAL TECHNOLOGIES in-house team of force protection experts and application engineers work hand-in-hand with owners, engineers of record, blast consultants and general contractors to develop the best solutions from a wide range of products. By partnering with design professionals we assist in solution development by providing:

    • Determination of blast loads and pressures
    • Analysis of blast capacity and performance determinants
    • Blast mitigation conceptualization and option development
    • Detailed high-fidelity analysis and design of mitigation options
    • Structural design of blast mitigation solutions

    Assessment of Structural Capacity for Blast


    Each product in STRUCTURAL TECHNOLOGIES force protection line can be custom engineered by our application engineering group to adjust to your specific project needs. Often multiple product solutions are combined and modified to optimize both performance and value.

    Collaboration with our in-house contracting services that understand constructability, schedule and construction costs ensure all elements of the project are taken into account in developing the highest value solution.

    Force Protection Engineering Team Leader
    Tarek Alkhrdaji, PhD, P.E.

    Tarek Alkhrdaji, PhD, PE

    Tarek Alkhrdaji, PhD, PE, is Vice President of Engineering with Structural Technologies, Hanover MD. He received his Masters and Ph.D. degrees at the Missouri University of Science and Technology. Dr. Alkhrdaji has experience in structural repair and strengthening and full scale load testing of concrete structures. He has been involved in more than 400 projects involving structural repair and strengthening and was involved in numerous repair and strengthening projects that received awards from The American Concrete Institute (ACI), the Post-Tensioning Institute (PTI), and the International Concrete Repair Institute (ICRI). Dr. Alkhrdaji also has experience in design, planning and execution of full-scale load testing of structures for strength evaluation and performance verifications. such as ACI, ASCE, AWWA, SEA, PTI, and ICRI. Dr. Alkhrdaji is currently an active member of He is also an active member of ACI Committee 437 (Strength Evaluation of Existing Concrete Structures), ACI Committee 562 (Concrete Repair Code), a member of ASCE (American Society of Civil Engineers), ICRI (International Concrete Repair Institute) and AWWA (American Water Works Association).

    Dr. Alkhrdaji has written more than 40 papers and articles on structural strengthening of structures including buildings, bridges, silos, tanks and concrete pipes. He has made many technical presentations at major industry events, professional organizations seminars and conferences and was the past Chair of ACI Subcommittee 440F (FRP Repair & Strengthening).



    STRUCTURAL TECHNOLOGIES' licensed engineering services are provided by Structural Technologies StrongPoint, LLC - A Structural Group Company, or through other licensed engineers.

    Installation Support


    STRUCTURAL TECHNOLOGIES provides construction phase support services to ensure that the force protection systems are installed properly and will carry out their intended functions. We coordinate with builders to provide project-specific oversight, quality assurance and quality control.

    Turnkey Investigate – Design – Build Solutions

    When paired with Structural Group's specialty contracting companies—we provide our clients with a full range of force protection design support, construction, and maintenance services from a single source of accountability. Together, we seamlessly deliver customized, cost-effective, and long-lasting solutions for structural challenges.





    STRUCTURAL TECHNOLOGIES — A Structural Group Company

    With member companies dating back to 1902, Structural Group is firmly committed to its ongoing mission of making new and existing structures stronger and last longer. Through its member companies, Structural Group delivers turnkey solutions that integrate technology, engineering, and construction. Structural Group provides state-of-the-art products and engineering support services through STRUCTURAL TECHNOLOGIES and specialty contracting services through STRUCTURAL and PULLMAN

    Learn more about Structural Group and its member companies.