Arthaus, 311 Broad Street, Philadelphia, Pennsylvania

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Overview: Developed by Dranoff Properties, this 47-story residential tower at 311 Broad Street will feature a 524-foot-high tower with over 400,000 SF of living space, a 5-story podium, and one level of below-ground parking. The project’s estimated cost is more than $253 million. GeoStructures conducted a geotechnical investigation and design services for the proposed development, as well as on-going construction inspection and testing.

Test borings including rock coring were carried out to characterize the subsurface conditions for foundation and construction. A mat foundation was selected as the optimal system. Further PMT testing was undertaken by GeoStructures to effectively determine settlement of the mat under the tower. The use of the mat foundation over the caissons saved approximately $1.5 million. Caissons were utilized to support the podium in non-basement areas along the south end to prevent stressing the historic church basement walls.

Foundation settlement analysis was performed using a 2-D FEM program (SIGMA/W) to evaluate the soil-structure interaction among the tower mat, the podium footings, and the adjacent Center City One high-rise. A combination of spread footings and caissons (south end) were used for support of the podium.

Since the groundbreaking in June 2019, GeoStructures has been performing all of the special inspection services for this concrete structure including a nearly 4000 CY mat, grade beams, footings, cast-in-place concrete, rebar, floor flatness and levelness, floor edge profile, structural steel, sprayed fireproofing and intumescent paint, and laboratory testing of high strength concrete up to 14,000 psi.

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Percolation and Permeability In-Situ Testing 

Drilling Services and Subsurface Investigations

Foundation Investigation and Design

Highway and Bridge Geotechniques

Support of Excavation and Underpinning

Soil-Structure Interaction Analysis and Modeling

Soil Dynamics & Site-Specific Response Spectra

Vibration Monitoring and Analyses

Forensic Evaluations

Slope and Retaining Wall Evaluation and Design

Lime and Cement Stabilization

Mine Subsidence Analysis and Remediation

Sinkhole Evaluation and Remediation

Soil Improvement Techniques

Dam Analysis and Rehabilitation

Environmental Services

Landfills, Ponds, and Lagoons

Pavement Design and Rehabilitation

Construction Inspection and Materials Testing

Geotechnical Laboratory Testing

Concrete and Cement Testing

Petrographic Analysis

Instrumentation and Special Testing

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