Minhaj Kirmani

Unbraced Circular Cofferdam for Boston's Third Harbor Tunnel

Restructuring: America and Beyond, 1995

Precast/Prestressed Slurry Walls with Tie-backs for the Hotel at the World Trade Center in Boston, MA

Building to Last, 1997

It's All in the Bracing

Civil Engineering, Mar 1, 1999

When the Massachusetts Bay Transportation Authority (MBTA) hired Weidlinger Associates Inc., Camb... more

Composite T-Panel Slurry Walls Adjacent to the Historic State Street Block

... CE Database Search | Descriptions | Search Tips | Subject Heading List. Composite T-Panel Slu... more

Shoring Measurements at Museum Towers

Temporary shoring supports for slab-style concrete building construction have a history of collap... more Temporary shoring supports for slab-style concrete building construction have a history of collapse. Hadipriono and Wang (1986) reported 85 collapses in 25 years. In order to establish better shoring procedures, shore loads were measured simultaneously in 20 shores in a 26-story building as it was built. The building was part of the Museum Towers at North Point complex in Cambridge, MA. The construction sequence was moderately fast track. Up to five stories of shoring were in place at one time. Loads were measured at 10 locations that spanned 2 columns of shoring cycles during pouring, curing and form removal activities.

Precast/Prestressed Slurry Walls with Tie-backs for the Hotel at the World Trade Center in Boston, MA

It's All in the Bracing

When the Massachusetts Bay Transportation Authority (MBTA) hired Weidlinger Associates Inc., Camb... more When the Massachusetts Bay Transportation Authority (MBTA) hired Weidlinger Associates Inc., Cambridge, Mass., to renovate the Aquarium Station stop along the subway system's Blue Line in 1989, one of the firm's greatest challenges was protecting the State Street Block (SSB), a row of wharf buildings constructed in the 1850s. Protecting these structures, as well as the existing subway tunnel, called for a reliable bracing system that would minimize soil movement during excavation for the new entrance. A composite T-panel slurry wall system kept lateral wall deformation to less than an inch and shaved $1 million and a year's construction time off the project. The choice of structural steel rather than concrete as the system's web will save even more time when construction is finished and portions of the web are removed.

Unbraced Circular Cofferdam for Boston's Third Harbor Tunnel

Achieving LOW Floor-to-Floor Heights

Download

Modular Construction Mold Apparatus and Method for Constructing Concrete Buildings and Structures

It's All In the Bracing

Civil EngineeringASCE, 1999

When the Massachusetts Bay Transportation Authority (MBTA) hired Weidlinger Associates Inc., Camb... more

Composite T-Panel Slurry Walls Adjacent to the Historic State Street Block Minhaj Kirmani1, Steven Highfill2, Gorden Chen3

… of Sessions of …, 1998

One Lincoln Street Arched Slurry Wall

One Lincoln Street is one of the most recent buildings constructed in downtown Boston. Its struct... more One Lincoln Street is one of the most recent buildings constructed in downtown Boston. Its structure consists of a 36-story high-rise building directly connected to a 7-story low-rise building. Its substructure has five levels of underground parking garage to accommodate 900 cars in a city where prime real estate is becoming scarce. The excavation for the underground parking garage was supported by reinforced concrete slurry walls, which also serve as the substructure's permanent walls. The stiffness of the slurry walls, together with the strut and tieback bracing system, minimized movement during excavation, which occurred in close proximity to existing buildings. Of particular interest is the northwest corner of the excavation, which was supported by an arched slurry wall, possessing a shape in plan of a quadrant of a circle with a radius of 50 feet. This paper presents key aspects of the analysis, design, construction and performance of the arched slurry wall. While the other slurry walls in the project were designed to support the 59 foot deep excavation with two levels of bracing, a remarkable feat by itself, the 3 foot thick arched slurry wall was analyzed, designed and constructed to support the excavation with no bracing. The analysis consisted of two-dimensional finite element models, modified to include the effects of three-dimensional arch action. Predicted lateral movement of the wall was minimal, having minor impact to adjacent structures, and measured inclinometer readings favorably support the predicted movements.

One Lincoln Street Arched Slurry Wall

One Lincoln Street is one of the most recent buildings constructed in downtown Boston. Its struct... more One Lincoln Street is one of the most recent buildings constructed in downtown Boston. Its structure consists of a 36-story high-rise building directly connected to a 7-story low-rise building. Its substructure has five levels of underground parking garage to accommodate 900 cars in a city where prime real estate is becoming scarce. The excavation for the underground parking garage was supported by reinforced concrete slurry walls, which also serve as the substructure's permanent walls. The stiffness of the slurry walls, together with the strut and tieback bracing system, minimized movement during excavation, which occurred in close proximity to existing buildings. Of particular interest is the northwest corner of the excavation, which was supported by an arched slurry wall, possessing a shape in plan of a quadrant of a circle with a radius of 50 feet. This paper presents key aspects of the analysis, design, construction and performance of the arched slurry wall. While the other slurry walls in the project were designed to support the 59 foot deep excavation with two levels of bracing, a remarkable feat by itself, the 3 foot thick arched slurry wall was analyzed, designed and constructed to support the excavation with no bracing. The analysis consisted of two-dimensional finite element models, modified to include the effects of three-dimensional arch action. Predicted lateral movement of the wall was minimal, having minor impact to adjacent structures, and measured inclinometer readings favorably support the predicted movements.

Download

Experimental and Analytical Verification of the ''Tuned Strut'' Concept

Structures Congress 2006, 2006

Deep excavations require bracing along the wall height to resist lateral earth pressures. Design ... more Deep excavations require bracing along the wall height to resist lateral earth pressures. Design of a typical straight strut is influenced by self-weight bending stresses acting simultaneously with axial stresses. As length increases beam-column actions and second order effects (P-δ) can significantly reduce the axial load carrying capacity of the strut. Long struts therefore need to be supported intermittently, using “pin-piles”, resulting in additional cost and inefficiencies associated with congestion in the excavation trench. Additionally there can be problems associated with leakage of water in the invert slabs due to penetration in the waterproofing system around the “pin-piles”. Weidlinger Associates has proposed the use of a cambered, or “tuned”, strut [1]. In this design a long span twin I-girder strut is cambered upwards, such that the P-δ effects partially offset the gravity induced bending stresses. This could result in minimized bending stresses and optimal strut axial capacity, minimizing the need for intermediate supports. This paper describes an experimental and analytical research program in which scaled strut models were tested. The deflection and strain of axially loaded struts of varying length and camber were compared to a finite element analysis to verify concept and establish design recommendations.

Precast Prestressed Slurry Wall for Pilot House Project

Uploads

Papers by Minhaj Kirmani

Log In