Robert F. Kennedy Bridge, Seismic and Wind Investigation

Queens, NY

Client: Thornton Tomasetti Owner Name: TBTA

The RFK Bridge is a major link between Manhattan, the Bronx, and Queens. The original portion of the Queens approach was built in 1936 and rehabilitated in 1996 and again in 2000. With an overall length of 507 feet, the structure consists of 22 spans, including a reinforced concrete rigid frame that spans 27th street in Queens, NY.


As a sub-consultant to Thornton Tomasetti, MP Engineers provided seismic analysis
of the Queens approach of the RFK Bridge. Utilizing available contract drawings, a full length, three dimensional (3-D) finite element model was created to capture the geometry of the superstructure and substructure features to the fullest extent possible.


CSiBridge Advanced V15.2 software developed by Computers and Structures, Inc.
was used to perform the structural analysis. All members, including bridge deck, steel stringers, elastomeric bearings with calculated stiffness, concrete cap beams and concrete columns, and foundation spring were modeled using 3D Space frame (beamcolumn) members or shell elements or link elements as applicable.


Modal analysis was performed to identify the natural period, natural frequencies, and
mode shapes of the structure. Response spectrum analysis was performed to evaluate the seismic behavior of the approach. All substructure members were evaluated for two levels of Earthquake (Functional evaluation earthquake with a 10% probability of exceedance in 50 years corresponding to a return period of about 500 years and Safety evaluation earthquake with a 2% probability of exceedance in 50 years corresponding to a return period of 2500 years) as per the design criteria and using FHWA and AASHTO guide specifications for LRFD Seismic bridge design.


The vulnerability report was prepared and evaluation of each member was expressed
in terms of a demand/capacity (D/C) ratio. A sensitivity study was also conducted to
evaluate the effects of change in soil spring stiffness. Spring stiffness of +50% was
used to evaluate the D/C ratio sensitivities of concrete cap beams and concrete piers.

  • Structural Investigation