The iconic construction hard hat, a symbol of pride for the construction worker, has changed very little in 50 years. Developments in the understanding of the causes and prevention of debilitating and often fatal head injuries is leading to a revolutionary change in the way we protect our people from head injuries on the jobsite. The classic hard hat is about to change forever. This presentation will focus on new technology available today to minimize the effects of falls and impacts to the head of the worker. We will also focus on new technologies, already in development, that can further provide protection from head injuries. Industry requirements (OSHA, ANSI) will be reviewed, and the application of worldwide standards (EN) will be discussed and applied to new helmet development and implementation.
Richard Miller Treatment Plant is a 240 mgd cap. potable water treatment facility located in the California area of the Cincinnati, Ohio, US. After installing an advanced ultraviolet (UV) disinfection treatment system in 2013, GCWW became the largest water utility in North America to use UV light following sand filtration and granular activated carbon. The concrete filter gallery building was originally constructed in 1907 with 26 filters, with a 14-filter addition in 1937 and 7 filters added in 1964. After over 110 years of service, the structures started showing significant signs of deterioration, most commonly concrete spalling and reinforcing steel corrosion. This case study will highlight the methods used to evaluate the structures that involved conventional methods such as sounding, crack mapping, chemical and petrographic examinations, along with technology such as Half-Cell Potential/ICOR, Impact-Echo, Ground Penetrating Radar, and UAS (Drone) services.
Shotcrete has been used widely for rehabilitation and retrofit of concrete structures. More and more large infrastructures, in particular, in the hydro power industry, is using shotcrete for major rehabilitation and retrofit. Recently, the US Army Corps of Engineers has been engaged in structural modifications to reinforced concrete draft tube exits from the turbines in the Ice Harbor Lock and Dam located on the Snake River, Washington. This presentation details the structural modification to the draft tube which was successfully completed using wet-mix shotcrete.
Arrowhead Stadium originally opened in 1972 and is known to be the home to the Super Bowl Champions Kansas City Chiefs. Renovations of the stadium completed in 2010 included adding luxury suites on the club level of the stadium. This meant that the upper seating bowl not only had to seat more than 34,000 Chief fans but also act as a "roof" for the new luxury suites. The upper seating bowl comprises L-shaped precast concrete seating risers spanning from cast-in-place concrete raker beams and is divided by sixteen expansion joints. In 2018, the planning for the upper seating bowl waterproofing program began. The goal for the repair project was to implement waterproofing upgrades to protect the concrete for the next 10 years. To add to the challenge of a large-scale waterproofing and structural repair project, the construction efforts had to include coordination with simultaneous seat replacement to be completed in a single off-season.
This presentation looks at buildings that are new or being rehabilitated and the impact on making buildings more energy efficient. Starting with the 2012 IBC, and specifically the 2012 IECC portion of the building code and newer versions, the presentation will look at three aspects of the building envelope: Water Resistance, Air Leakage, and Moisture Transmission. It will then compare to identical buildings, the first built in 2000 and the second constructed in 2020. Illustrations and calculations will show how controlling air leakage can have an enormous impact on the service life of the structure, initial cost of construction, and on-going operations. Lastly, the presentation will look at how incorporating simple additions during the repair/rehabilitation process can have a positive impact on the environment as well as the building owner and the building’s constituents.
The presentation, through case studies, talks about emergency response services for structural issues encountered during construction of new design projects. Among other examples is an eleven story precast parking structure. The contractor observed significant diagonal faulted cracking of L-beams (supporting double-tee sections) near bearing locations, few days after pouring topping slab. In addition, inverted-tee girders were observed to be supported on cracked corbels at other locations. A quick turn around was required to mitigate any immediate life safety hazard posed by the structural distresses and buy time for thorough investigation, non-destructive testing, analyses, and repair design. Another example is a seven story precast parking structure. The structure was under construction and reportedly erected out of plumb. Poor concrete placing practices and poor weld detailing led to widespread cracking in multiple structural elements throughout the structure...
Historic 19th and 20th century buildings are currently facing the necessity of meeting contemporary needs such as adaptive re-use, energy efficiency, stability, and durability. The characteristics of architecture of these periods (i.e., material, design, details, maintenance, and functionality) increasingly make it challenging to maintain authenticity while incorporating new uses. Various strategies of technical interventions can be employed to achieve good results. This presentation will cover the case study of abandoned historic hospital pavilions from the early 20th century which are being converted into a high-end residential complex. The buildings face multiple challenges related to adaptive re-use, as they will be restored and connected with new infills and a glass connector and capped with re-creation of the historic cornices.
A follow-on presentation to the discussion of our evaluation of over 1500 tire and lube facilities across the United States that prescribed immediate repairs where necessary, reinforcement where deterioration reduced capacity below acceptable levels and coatings necessary to protect structural steel and structural concrete (i.e. our 2019 Philadelphia presentation). This will be an in-depth presentation of how repairs were specified for (3) specific types of structures. The (3) structure types are exposed structural concrete, composite metal deck and fully reinforced form deck slabs all supported by steel structures and reinforced concrete walls. Presentation will include before, during and completion photos of each project discussed. Again, touch on the evaluation processes to include demand to capacity ratios review, evaluation system and inspection form, triggers to determine when shoring is necessary, calculation of capacities per AISC 360, ACI 318, ACI 562 and local building codes.
Nondestructive testing is often used in conjunction with traditional methods to assess construction, material, or structural deficiencies in new construction. This presentation describes evaluation of unique delamination failures within below-grade, exterior walls of a new subway station. The walls were conventionally reinforced mass concrete cast against a soldier pile and lagging retention system. Shortly after construction, leakage at cracks and joints was observed and injection processes led to delamination of the interior surfaces. The assessment objectives were to determine the extent and cause of near-surface discontinuities and evaluate the structural integrity of the walls. Nondestructive testing included flaw detection using Impulse Response [structural mobility testing] and reinforcement locating using ground-penetrating radar. Sampling and petrographic examinations were conducted to correlate test results with distress conditions and evaluate the in-situ concrete.
Este lineamiento proporciona una guía sobre la remoción de concreto y los procedimientos para la preparación de la superficie paray la reparación del de concreto deteriorado provocado por la corrosión del acero de refuerzo. Se discuten la geometría de la remoción, la configuración del área de reparación, el proceso de remoción, la preparación del borde, la reparación del refuerzo, la preparación e inspección de la superficie necesarias para las reparaciones durables. Se incluyen consideraciones especiales para la remoción de concreto asociada con la reparación de columnas.