Practice Periodical on Structural Design and Construction

The way people interact, collaborate, learn, and improve can have a profound impact on an organization's efficiency, performance, productivity, and return on investment. This is the motive behind corporate efforts today to replace traditional hierarchical structures with team-oriented organization. Teamwork is an integral part of the construction process, and construction companies have pioneered “partnering” and subcontracting as a standard way of doing business. Still, the typical construction company today adheres to hierarchical management approaches that inhibit open communication, trust, collaboration, and the rapid response to change that is necessary to sustain a competitive advantage. Transforming hierarchical management structures into efficient, process-oriented organizations can be implemented through thoughtful, well-planned reorganizational strategies, beginning with (1) a commitment to change; (2) companywide adoption of mutual values and agreed behaviors; (3) a team-building strategy; (4) commitment to learning and knowledge transfer; and (5) training to improve technical breadth, teamwork, and leadership skills. The ultimate goal is a dynamic team culture where manager and employee grow and prosper together.

Cast and wrought-iron bridges across the Enlarged Erie Canal built by Squire Whipple, or to his 1841 patent, were commonplace in the period of the early 1840s up to the opening of the New York State Barge Canal in the second decade of the 20th century. Many bridges were removed and sold to private land owners for their use, and some were scrapped by the state. This article traces the history of one of his bridges and its recent rehabilitation and reconstruction over a portion of the Enlarged Erie Canal at Vischer's Ferry, New York. Students and friends of Union College successfully rebuilt the bridge, stone abutments, and approaches with no state, federal, or town funding. It stands as a tribute to what can be done to preserve the heritage of American civil engineering.

In many situations designers are faced with the problem of a building addition that requires new columns near, or directly above, existing foundations. Several design alternatives are usually considered, and frequently the desired objective is to minimize the impact on the existing foundations. The impact can be minimized by altering the substructure support system or by altering the design of the new building. Alternatives such as cantilevered grade beam systems supported by caissons, or the utilization of cantilevered beams in the superstructure, allow designers to setback the new column line from the existing foundations. The setback minimizes the effects on the existing foundations. The alternatives are usually explored fairly quickly and are precipitated by the desire to avoid a complicated and, perhaps, expensive analysis/design effort that may involve underpinning of the existing foundation. In some cases, alternatives are limited, and utilization of existing foundations, with appropriate modifications, is the only reasonable approach. Modifications of the existing footing to ensure that the allowable soil bearing capacity is not exceeded and that proper load transfer occurs between the existing foundation and additions thereto are critical to this approach. The analysis effort is heavily dependent on the utilization of current computer technology to quickly ascertain the load effects on existing foundations due to the new building columns. Engineering analysis software can be used to quickly determine the modifications that are required to accommodate the new column loads. During a recent design/analysis effort, current engineering analysis software was employed to ascertain the effects of new column loads on existing foundations. The analysis led to design modifications that allowed the new columns to be placed in close proximity to the existing building columns and placed directly onto existing foundations. The design/analysis process consisted of many important steps that ranged from establishing confidence in the computer model to final design modifications based on stress contour plots and basic strength of materials principles. A description of the analysis process and overall conclusions are presented herein.

Keysville Road Bridge is an 1880 wrought-iron truss bridge listed on the U.S. National Register. The bridge is across Tom's Creek, located in Frederick County, Maryland. This 31.4-m-(103 ft)-long structure has an overall width of 4.57 m (15 ft 0 in.) c/c of the trusses and 3.66 m (12 ft 0 in.) clear roadway between timber curbs. The trusses are wrought-iron Warren trusses with eight panels spaced about equally. This historical bridge was damaged by the previous year's flooding. During the flood, the bridge, which was then covered with canvas for painting, was uprooted by the high water and displaced several yards downstream. The bridge was recently rehabilitated and repainted. Several bent and damaged truss members, including all of the deck, were restored. All the replaced truss members are A36 steel and the deck panels are treated glue-laminated woods. Some of the truss members were recovered from damage and the integrity of the whole truss structure was the concern of the county officials. A field test by using strain gauges was conducted by the Bridge Engineering Software and Technology (BEST) Center, Department of Civil Engineering, University of Maryland. While the bridge was undergoing testing, rehabilitation was nearly completed except for the railing. The complete test was done and with the load-proofing the bridge was opened to traffic.

This paper discusses three examples of construction failures. The first example shows how differential foundation settlement between two structures can destroy bracing members in a structure, if this bracing is redundant to the stability of the structure. The second example discusses a case where the designer made the wrong assumptions in the boundary conditions of the structure. The consequence was a construction failure and an expensive design change. The third example shows how a change in the construction sequence, due to acceleration of the construction schedule, led to a construction failure with subsequent expensive delays and reconstruction. The paper concludes with the suggestion that these types of construction failures can be avoided by employing better engineering practices in design and construction, such as checking and reviews of designs and construction procedures.