Many researchers have identified concerns with steel corrosion in concrete structures. This thesis investigates the serviceability of concrete structures reinforced with Fiber Reinforced Polymer (FRP) material. The distinctive properties of the reinforcement influence the analysis and design of structures. An alternate expression for effective moment of inertia was derived to consider these differences and improve the estimation of deflection for concrete beams reinforced with FRP. Serviceability issues encountered with FRP reinforced concrete structures were also addressed by exploring Prestressed Concrete Prisms (PCPs) as reinforcement. They are small sections of high strength concrete cast around a concentrically pre-tensioned FRP reinforcing bar. The technique enhances axial stiffness of the bar and flexural stiffness of concrete beams. Thermal weathering was investigated by subjecting beams to temperature fluctuations expected in the Canadian climate. Inclusion of dispersed fibers in the PCP reinforcement and surface deformations was also studied to determine the influence on post-cracking behaviour.

Many researchers have identified concerns with steel corrosion in concrete structures. This thesis investigates the serviceability of concrete structures reinforced with Fiber Reinforced Polymer (FRP) material. The distinctive properties of the reinforcement influence the analysis and design of structures. An alternate expression for effective moment of inertia was derived to consider these differences and improve the estimation of deflection for concrete beams reinforced with FRP. Serviceability issues encountered with FRP reinforced concrete structures were also addressed by exploring Prestressed Concrete Prisms (PCPs) as reinforcement. They are small sections of high strength concrete cast around a concentrically pre-tensioned FRP reinforcing bar. The technique enhances axial stiffness of the bar and flexural stiffness of concrete beams. Thermal weathering was investigated by subjecting beams to temperature fluctuations expected in the Canadian climate. Inclusion of dispersed fibers in the PCP reinforcement and surface deformations was also studied to determine the influence on post-cracking behaviour.

Low-amplitude floor vibrations have become a governing serviceability performance design consideration for floors constructed with low mass-to-stiffness ratio materials such as wood. Studies reported here were conducted at the University of Ottawa to assess vibration serviceability performance of glued-laminated-timber (glulam) beam-and-deck floor systems. Such floors are applicable in non-residential buildings having spans up to about 10 m. The primary goal was to use test and numerical analysis methods to investigate how construction variables (e.g. beam span, beam spacing, addition of nonstructural overlays) affect the vibration responses of such floors. A secondary goal was to assess applicability of vibration serviceability design criteria proposed for other types of floors to glulam beam-and-deck floors. Apart from tests aimed at characterizing responses of laboratory built rectangular plan floors, focus groups were asked to subjective rate acceptability of the performances of those floors. Focus group ratings determined ability of humans to discern alterations in floor motions resulting from construction modifications, based on an opinion survey technique developed by other researchers. This determined that humans can detect and rate performance of floors having different engineering design characteristic, but cast doubts on the consistency of the employed opinion survey technique. Laboratory tests revealed that mid-span displacements of floors are functions of two-way deflected shapes of floors and are reduced by adding nonstructural overlays and extra beams. Adding non-structural overlays reduces fundamental natural frequency demonstrating gain in modal mass was greater than for modal stiffness. There was inconsistency between the result of focus group evaluations and predictions of acceptability of floors made using available suggested vibration serviceability design criteria. Finite Element (FE) models of glulam beam-and-deck floor systems were created and verified using laboratory test data. Based on those models it was concluded that fundamental natural frequencies and mid-span displacements of floors are relatively insensitive to variations in floor width-to-span ratios. However, higher order natural frequencies are strongly affected by floor width-to-span ratios. Increasing thickness of deck elements can decrease natural frequencies and cause them to cluster in ways that amplify surface motions caused by dynamic forces like human footfall impacts. Field vibration tests were conducted to investigate the dynamic behaviour of a large glulam beam-and-deck office floor having a complex plan shape and support conditions. That floor has long beam spans and partial continuity between bays defined by a mixture of column and wall supports. It was tested before non-structural floor toppings were added and after building completion and occupation. FE modeling of the floor was created and predicted modal characteristics (i.e. mode shapes, natural frequencies) compared with experimentally derived ones. Controlled walking tests were conducted to assess the dynamic response under office occupation conditions. It was concluded the vibration serviceability response of the floor was satisfactory based on peak acceleration measurements and lack of office worker dissatisfaction. Importance of this is the floor has low order natural frequencies less than 8Hz, which means existing proposed design practices created for lightweight timber floor would incorrectly classify its performance. The discrepancy is indicative that such design practices fail to capture effects of construction variables and damping characteristics of large floors. In general, vibration characteristics of lightweight floors are highly related to effects of construction details such as plan aspect ratio, boundary conditions and presence of nonstructural elements. Apart from clarifying specifics of how glulam beam-and-deck floors vibrate, this thesis is intended to contribute to Canadian and international efforts to create engineers design methods that robustly predict whether or not specific floors will have adequate vibration serviceability performance under defined floor occupancy conditions.

Several different aspects of floor vibrations were studied during this research. The focus of the research was on developing a computer modeling technique that will predict the fundamental frequency of vibration and the peak acceleration due to walking excitation as given in AISC Design Guide 11, Floor Vibrations Due to Human Activity (Murray, et al., 1997). For this research several test floors were constructed and tested, and this data was supplemented with test data from actual floors. A verification of the modeling techniques is presented first. Using classical results, an example from the Design Guide and the results of some previous research, the modeling techniques are shown to accurately predict the necessary results. Next the techniques were used on a series of floors and the results were compared to measured data and the predictions of the current design standard. Finally, conclusions are drawn concerning the success of the finite element modeling techniques, and recommendations for future research are discussed. In general, the finite element modeling techniques can reliably predict the fundamental frequency of a floor, but are unable to accurately predict the acceleration response of the floor to a given dynamic load. / Master of Science

The design of steel framed buildings must take into consideration the lateral drift of the structure due to wind loading and any serviceability issues that may arise from this lateral movement. This thesis focuses on one of these issues, damage to nonstructural components. Although there are no specific requirements in the United States governing the effects of wind drift, it is an important issue which may significantly impact the buildings structural performance and economy. Furthermore, because these serviceability issues are not codified, there is a wide variation among design firms in how they are dealt with, leading to a greater economic disparity. This thesis begins with a comprehensive review of the literature that covers all pertinent aspects of wind drift in steel framed buildings. Next an analytical study of the variations in modeling parameters is performed to demonstrate how simple assumptions can affect the overall buildings stiffness and lateral displacements. A study is then carried out to illustrate the different sources of elastic deformation in a variety of laterally loaded steel frames. The different modeling variables demonstrate how deformation sources vary with bay width, the number of bays and the number of stories, providing a useful set of comparisons. To ascertain how serviceability issues are dealt with from firm to firm, a survey of the practice is developed to update the one conducted in 1988 (ASCE). In effect, the thesis is presented with the intention of suggesting and establishing a comprehensive, performance based approach to the wind drift design of steel framed buildings. / Master of Science

Several recently built inverted-T bent caps in Texas have shown significant inclined cracking triggering concern about current design procedures for such structures. The repair of such structures is very costly and often requires lane closures. For these reasons TxDOT funded Project 0-6416 aimed at obtaining a better understanding of the structural behavior of inverted-T bent caps and developing new design criteria to minimize such cracking in the future. Several tasks of the aforementioned project are addressed in this dissertation with particular focus on developing design criteria for strength and serviceability of inverted-T bent caps. Literature review revealed a scarcity of experimental investigation of inverted-T specimens. As part of this dissertation, an inverted-T database was assembled with experimental results from the literature and the current project. An extensive experimental program was completed to accomplish the objectives of the project with thirty one full-scale tests conducted on inverted-T beams. Experimental parameters varied in the study were: ledge length, ledge depth, web reinforcement, number of point loads, web depth, and shear span-to-depth ratio. The dissertation focuses on the effects of ledge length, ledge depth, number of point loads, and developing design criteria for strength and serviceability of inverted-T beams. Most inverted-T bent caps in Texas are designed using the traditional empirical design procedures outlined in the TxDOT bridge design manual LRFD (2011 current version) that follows closely the AASHTO LRFD bridge design specifications (2012 current version). Given the observed cracking in inverted-T bent caps, the accuracy and conservatism of the traditional design methods were evaluated based on experimental results. The accuracy and conservatism of STM design provisions recently developed in a TxDOT study (TxDOT Project 0-5253, Strength and Serviceability Design of Reinforced Concrete Deep Beams) were also evaluated. / text

The availability and use of new materials and construction techniques are allowing bridges to be built that are longer and more slender to those that have been constructed in the past. This can cause bridges to have lower stiffness and damping, and thus be less able to resist dynamic effects. This is of special concern for pedestrian bridges, because the harmonic loads that pedestrians apply to the bridge have the potential to excite the bridge’s natural frequencies. In addition, pedestrians can be sensitive to these vibrations. A model was developed in order to better understand the effects that a pedestrian can have on these vibration-prone bridges. The model consisted of two parts: a finite element model that used the structural data for the bridge in order to produce mass-normalized mode shapes, and a bridge-pedestrian interaction program that used the structural and modal data, along with pedestrian loading scenarios, to generate the bridge response. A parametric study of two bridges was conducted. The bridges included: a short span bridge that would not be expected to respond excessively to pedestrian loads, and a long-span, lively bridge that had natural frequencies in the range of pedestrian loading. Many loading cases were examined by varying the following parameters: load case, number of pedestrians, damping, and pacing frequency. The modal solution was an effective method of finding the bridge responses. It was determined that pedestrian loads can be represented by a simple constant plus sinusoidal load. The excessive vibrations of long and slender bridges could be addressed by increasing damping on susceptible modes. / Thesis (Master, Civil Engineering) -- Queen's University, 2010-05-03 12:36:05.561

While designing metal buildings for wind drift, for simplicity of analysis and design, connection at base of column is considered as pinned which provides no rotational restraint. The actual behavior of the connection however, is partially rigid, that provides some rotational stiffness even in case of single row of bolts. Moreover, using a two-dimensional (planar) structural model for analysis ignores any load distribution provided by roof and wall sheeting. Simulation of true behavior of base connection and diaphragm stiffness can substantially reduce drift caused due to lateral forces thereby lessening the conservatism in traditional design practices. This thesis provides results obtained from full-scale experimental testing and analytical study for a metal building. A full scale load test was conducted to quantify the lateral stiffness of an existing metal building. A static lateral load, consistent in magnitude with the building's design wind pressure, was applied to the knee of a primary frame, and the resulting lateral displacements and column-base rotations for all primary frames were measured. The test procedure was repeated at several locations. The experimentally obtained results were then validated using two-dimensional and three-dimensional analytical models. The three-dimensional models explicitly simulated the primary and secondary framing, roof and wall diaphragms, and column-base stiffness. A couple of approaches have been proposed to model column-base plate connection varying in complexity and accuracy. Once validated, the FE model is utilized to quantify the relative stiffness contributions of the metal building system components to lateral drift. While performing analysis some other parameters were also studied. These consisted of effect of base plate thickness and length of anchor bolts on column-base rigidity. Also, effect of including shear deformations and considering the haunch (column-rafter junction) as rigid were studied. Another small but important part of the paper is comparison of wind pressures obtained using different procedure of ASCE 7-05 with database assisted design pressures. Once these parameters are quantified practical engineering guidelines are developed to incorporate the influence of secondary framing, roof diaphragms, wall cladding, and column-base stiffness and wind loads in metal building design. / Master of Science

Over the last decade, a number of reinforced concrete bent caps within Houston, Texas have exhibited premature concrete damage (cracking, spalling and a loss of material strength) due to alkali-silica reaction (ASR) and/or delayed ettringite formation (DEF). The alarming nature of the severe surface cracking prompted the Houston District of the Texas Department of Transportation to initiate an investigation into the structural implications of the premature concrete damage. Specifically, an interagency contract with the University of Texas at Austin charged engineers at Ferguson Structural Engineering Laboratory to: 1. Establish the time-dependent relationship between ASR/DEF deterioration and the shear capacity of affected bridge bent caps. 2. Develop practical recommendations for structural evaluation of in-service bridge bent caps affected by ASR and/or DEF. To accomplish these objectives, six large-scale bent cap specimens were fabricated within the laboratory. Four of the specimens (containing reactive concrete exposed to high curing temperatures) represented the most severe circumstances of deterioration found in the field. The remaining two specimens (non-reactive) provided a basis for the comparison of long-term structural performance. All of the specimens were subjected to a conditioning regimen meant to foster the development of realistic ASR/DEF-related damage. Resulting expansions were characterized over the course of the study through a carefully-planned monitoring program. Following a prolonged exposure period, three of the six bent cap specimens (representing undamaged, mild, and moderate levels of deterioration) were tested in shear. Observations made over the course of each test captured the service and ultimate load effects of ASR/DEF-induced deterioration. Six shear-critical spans were tested prior to this publication: three deep beam and three sectional shear tests. The remaining six shear spans (contained within the remaining three specimens) were retained to establish the effects of severe deterioration through future shear testing. Subsequent analysis of the expansion monitoring and shear testing data provided much needed insight into the performance and evaluation of ASR/DEF damaged bent structures. The results ultimately formed a strong technical basis for the preliminary assessment of a damaged bent structure within Houston, Texas. / text

In this study, a total of twelve beams continuous over two spans of 2,800 mm each were constructed and tested to failure. The beams were divided into two series. Series 1 included six T-beams under symmetrical loading, while Series 2 dealt with six rectangular beams under unsymmetrical loading conditions. In Series 1, the test variables included material type, assumed percentage of moment redistribution, spacing of lateral reinforcement in flange, arrangement of shear reinforcement, and serviceability requirements. In Series 2, three different loading cases were considered, I) loading both spans equally, II) loading both spans maintaining a load ratio of 1.5 and III) loading one span only. Under the loading case II, the parameters of reinforcing material type, assumed percentage of moment redistribution and serviceability requirements were investigated. The test results of both series showed that moment redistribution from the hogging to the sagging moment region took place in GFRP-RC beams which were designed for an assumed percentage of moment redistribution. In Series 1, the decrease of the stirrups spacing from 0.24d to 0.18d enhanced the moment redistribution percentage. Also, decreasing the spacing of lateral reinforcement in the flange from 450 to 150 mm improved the moment redistribution through enhancing the stiffness of the sagging moment region. In Series 2, the unsymmetrical loading conditions (loading case II and III) reduced the moment redistribution by reducing flexural stiffness in the heavily loaded span due to extensive cracking. Regarding serviceability in both series, the GFRP-RC beam designed for the same service moment calculated from the reference steel-RC beam, was able to meet the serviceability requirements for most types of the structural applications. / February 2017