SES Group & Associates (United States)

Coupled composite plate shear walls—concrete filled (CC-PSW/CFs) are an effective seismic lateral-force-resisting system for the design and construction of mid- to high-rise buildings around the world. The coupled system consists of two or more composite plate shear walls—concrete filled (C-PSW/CFs) connected to each other using composite coupling beams located at the story heights. The CC-PSW/CF system can provide higher overturning moment capacity, lateral stiffness, and ductility than uncoupled walls. Concrete-filled steel box sections are typically used for the composite coupling beams, which are designed to be flexure critical members. When the CC-PSW/CF system is subjected to lateral seismic forces, plastic hinge formation and inelastic deformations (energy dissipation) occur near the ends of most of coupling beams along the structure’s height, followed by flexural hinging of the C-PSW/CFs, typically at the base. This paper presents the details and design of four composite coupling beam-to-C-PSW/CF connection configurations. Six connection specimens representing the four connection configurations, with beam clear span-to-section depth, Lb/d, ratios of 3.5 and 5.1, were designed and tested. The lateral force-displacement and moment-rotation responses of the specimens are summarized. All six composite coupling beam-to-C-PSW/CF wall connection specimens (1) developed and exceeded the plastic flexural capacities, Mp, of the coupling beams calculated using the plastic stress distribution method and (2) developed chord rotation capacities greater than 0.03 radian before their flexural strength degraded to 80% of the plastic moment capacity, Mp.

Abstract Multiple initiatives advocate for reducing embodied carbon (i.e., greenhouse gas emissions) associated with concrete production. Even though readily implementable strategies exist, practitioners are concerned that reducing embodied carbon emissions may adversely affect concrete performance and durability, resulting in detrimental effects from a life cycle perspective. To address such concerns, this study investigated the correlations between embodied carbon of concrete mixtures, mixture design parameters, and experimentally measured mechanical and durability properties. The analyzed datasets included 145 mixtures, featuring a variety of mixture designs from laboratory and field studies. The results indicate that the cement content is the most significant predictor of global warming potential (GWP) and that considerable GWP savings can be achieved by reducing and replacing cement without compromising performance. Clear correlations of GWP with compressive strength were not identified, while the results demonstrated that reduced GWP and increased electrically based resistivity (the utilized durability indicator) often occur in synergy.

The goal of this method is to determine the chemical composition and electrical resistivity of cementitious pore solution expressed from a fresh paste sample. The pore solution is expressed from a fresh paste sample using a pressurized nitrogen gas system. The pore solution is then immediately transferred to a syringe to minimize evaporation and carbonation. After that, assembled testing containers are used for the X-ray fluorescence (XRF) measurement. These containers consist of two concentric plastic cylinders and a polypropylene film which seals one of the two open sides. The pore solution is added into the container immediately prior to the XRF measurement. The XRF is calibrated to detect the main ionic species in the pore solution, in particular, sodium (Na+), potassium (K+), calcium (Ca2+), and sulfide (S2-), to calculate sulfate (SO42-) using stoichiometry. The hydroxides (OH-) can be calculated from a charge balance. To calculate the electrical resistivity of the solution, the concentrations of the main ionic species and a model by Snyder et al. are used. The electrical resistivity of the pore solution can be used, along with the electrical resistivity of concrete, to determine the formation factor of concrete. XRF is a potential alternative to current methods to determine the composition of pore solution, which can provide benefits in terms of reduction in time and costs.

Amorphous nano-aluminosilicates are potentially seen as a new generation of nano-particle additives that can be used in cementitious materials. The primary objective of this research was to compare the effects of these novel nano-additives on the early hydration of Portland cement. The chemical and morphological changes undergone by the nano-particles as a result of exposure to cement pore solution were studied using Fourier transform infrared spectroscopy. The influence of the nano-particle solutions, or sols, on the cement hydration reaction was investigated using isothermal calorimetry. The results indicated a correlation between the arrangement of the aluminum within the silica framework and agglomeration of the nano-particles. Further, the effect of both these aspects on the hydration reaction of Portland cement is discussed.

Abstract This paper focuses on the coastal engineering aspects of the Oooguruk Project, which represents the third offshore production facility to be created in the Alaskan Beaufort Sea. The primary components of the project include a man-made island (" Offshore Drillsite??) constructed during the first nine months of 2006 in a water depth of approximately 4.5 ft, and a 5.7-mile subsea flowline bundle installed between the Offshore Drillsite and the mainland shore during the following winter. Due primarily to its location in shallow water, the Oooguruk Project is exposed to less severe wave and ice conditions than the two offshore production facilities constructed previously in the Alaskan Beaufort Sea. Nevertheless, significant design challenges were presented by the financial constraints imposed by smaller field economics, and by the project's location in an active river delta subject to vigorous strudel scouring. The 4-cy gravel bag armor selected for use on the Offshore Drillsite represents a cost-effective means of protecting the side slopes against wave and ice attack, based on the experience acquired at previous exploration and production sites in the Alaskan Beaufort Sea as well as the island's performance during its first year in existence. The long-term rate of bluff recession at the site of the Oooguruk flowline shore crossing, 3.3 ft/yr, reflects two distinctly different oceanographic regimes: periods dominated by easterly storms, when erosion is modest or negligible due to reduced water levels during storm events, and periods dominated by westerly storms, when elevated water levels promote rapid erosion by permitting storm waves to impact the bluff face. The data acquired over the past three years indicate that ice gouging of the seabed is of negligible importance in the Oooguruk project area. Conversely, strudel scouring is widespread and sufficiently energetic to expose the flowline bundle. Of particular concern are man-made slots or holes in the winter ice sheet created to facilitate installation or maintenance of the flowline, in that they may promote preferential scouring on the flowline route. Introduction The Oooguruk Project represents the third offshore production facility to be constructed in the Alaskan Beaufort Sea. As illustrated in Figure 1, the development lies approximately 40 miles west of Prudhoe Bay in the shallow deltaic waters off the East Channel of the Colville River. A man-made island known as the " Offshore Drillsite?? was constructed during the first nine months of 2006 in a water depth of approximately 4.5 ft (Plate 1), while a 5.7-mile subsea flowline bundle was installed between the Offshore Drillsite and the mainland shore during the following winter. The flowline bundle was buried in a trench excavated in the sea bottom to minimize the risk of damage from strudel scours and ice gouges. An overview of the field development is provided by Hall (2008), while the design of the civil facilities and pipeline bundle are discussed by Lucas, et al. (2008) and Lanan, et al. (2008), respectively. This paper focuses on the coastal engineering aspects of the Oooguruk Project, with emphasis on four specific topics:oceanographic design conditions,slope protection for the offshore drillsite,erosion of the mainland shore at the flowline shore crossing, andpotential disturbance of the flowline by ice gouges and strudel scours.

Abstract A civil engineering perspective is presented on the design and construction of exploration and production islands in the nearshore Alaskan Beaufort Sea. Pioneer Natural Resources' 2003 Thetis exploration ice islands and the subsequent 2006 Oooguruk production island in East Harrison Bay are highlighted. Engineering design issues are discussed including special techniques required for the severe ice, wave and permafrost environment. The effectiveness of using frozen gravel foundations, which must be designed for seabed settlement, gravel thaw-settlement and creep settlement, are discussed. Construction techniques and schedules have been developed to make use of the readily available ice and gravel. Monitoring performance is an important post-construction activity. Potential issues are identified with preventative and remedial solutions described. Three offshore exploration wells were drilled using conventional land-based equipment from grounded ice platforms during the course of one winter. Subsequently, a gravel production island was built in the same area using material hauled from shore. Seabed settlement and the thaw instability of frozen gravel are uniquely addressed in the design and construction of the island. An economical approach has been described for building temporary exploration structures and permanent production structures in shallow, protected nearshore waters of the Alaskan Beaufort Sea. The methods have applicability for accessing smaller offshore oil and gas fields in the Alaskan Beaufort Sea and in other cold regions of the world where similar marine conditions exist.

We present measurements of the emissions of the nitrogen oxide species nitric oxide, nitrogen dioxide, and nitrous acid in aircraft engine exhausts. In the Aircraft Particle Emissions Experiment test series, NO x (sum of nitric oxide and nitrogen dioxide) emissions were consistent with International Civil Aviation Organization certification measurements for a CFM56-2C1 engine, and the NO, emission index increases with increasing engine thrust At low powers, nitrogen dioxide represents up to 80% of the total NO x emissions for that engine, but this fraction decreases to 7% at the highest thrust setting. Nitrous acid, though a minor constituent (up to 7%) compared with NO,, is in part formed in the turbine through reaction with hydroxyl radical. It is therefore a sensitive monitor of exhaust chemistry through which chemical kinetic models capable of predicting concentrations of other important species, such as oxides of sulfur, can be validated. The CFM56 nitrous acid measurements are compared with previous observations, and a strong dependence on engine type is observed for both the nitrous acid emission index and its contribution to the emission index of the sum of all reactive gaseous nitrogen oxides. The nitrous acid emission index increases with increasing engine thrust, but the ratio of emission indexes of nitrous acid to nitrogen dioxide decreases with increasing thrust for the CFM56.