Design of Continuous Prestressed Concrete Spliced Girder Bridges

Traditionally, prestressed concrete girder bridges are limited to 150 ft span lengths in Texas due to restrictions on handling and transportation. An effective way of increasing span lengths of precast, prestressed concrete girder bridges is demonstrated using splicing technique. In spliced girder bridges, precast girder segments are transported in shorter segments for handling and transportation and then spliced together to form long-span continuous bridges. Different methods are explored for construction of spliced girder bridges. Two application examples are developed to demonstrate the design of continuous prestressed concrete spliced girder bridges for both shored and partially shored methods of construction. A three-span bridge having a span configuration of 190-240-190 ft is considered for both examples. Advantages and dis-advantages of each method of construction are discussed. Construction issues that should be considered in the design are highlighted. The results of this study indicate that span lengths up to 240 ft are achievable using standard Tx70 girders with the help of splicing techniques. A parametric study is performed to further explore the design space of spliced girder bridges. The results of the parametric study, along with critical design issues that were identified, are highlighted and related recommendations are provided. The results of this study will be of significant interest to bridge engineers and researchers for guidance in implementing spliced girder bridges in Texas and other states

Barrier island erosion and overwash study - volume 1

This is the first of a pair of reports documenting the effects of storms on barrier island systems. The present report (Volume 1) investigates storm effects on natural island conditions whereas Volume 2 addresses the effects of seawalls. With the aim of simulating the effects of overwash on barrier islands and characterizing their response, a series of nine experiments was conducted at the Coastal Engineering Laboratory of the University of Florida. The barrier island was simulated by a 400 feet wide (prototype units) horizontal crest and an initially planar (1:19) beach. The effects of various storm surge levels and accompanying overtopping were investigated. Experiments were conducted with both regular and irregular storm waves. Regular waves without overtopping caused the formation of a substantial berm in the swash zone and a prominent longshore bar offshore. Increasing degrees of overtopping resulted in substantial loss of sand from the barrier island system. The longshore bar was considerably more subtle for the highest water level tested (11.5 ft. above mean sea level). Simulation of a storm-surge hydrograph with rising and falling water levels indicated that the presence of the bar tends to occur only during a relatively steady or slowly changing water level. The experiments with irregular waves were conducted with reasonably similar wave heights and carrier periods as those with regular waves. The major difference was in the characteristics of the longshore bar response. In comparison with cases with regular waves, the bar was less distinct without overtopping, subtle with minimal overtopping and absent in cases with substantial overtopping. These experiments seem to indicate that offshore bars are simply break-point bars which require a fairly steady break-point and undertow (return of mass transport) for optimal formation. (Document has 84 pages.

Efficacy of virtual reality for pain relief in medical procedures: A systematic review and meta-analysis

BackgroundEffective pain control is crucial to optimise the success of medical procedures. Immersive virtual reality (VR) technology could offer an effective non-invasive, non-pharmacological option to distract patients and reduce their experience of pain. We aimed to evaluate the efficacy of Immersive virtual reality (VR) technology in reducing patient’s pain perception during various medical procedures by conducting a systematic review and meta-analysis.MethodsWe searched MEDLINE, EMBASE, CENTRAL, CINAHL, and SIGLE until December 2022 for all randomised clinical trials (RCT) evaluating any type of VR in patients undergoing any medical procedure. We conducted a random effect meta-analysis summarising standardised mean differences (SMD) with 95% confidence intervals (CI). We evaluated heterogeneity using I 2 and explored it using subgroup and meta-regression analyses.ResultsIn total, we included 92 RCTs (n = 7133 participants). There was a significant reduction in pain scores with VR across all medical procedures (n = 83, SMD − 0.78, 95% CI − 1.00 to − 0.57, I 2 = 93%, p = < 0.01). Subgroup analysis showed varied reduction in pain scores across trial designs [crossover (n = 13, SMD − 0.86, 95% CI − 1.23 to − 0.49, I 2 = 72%, p = < 0.01) vs parallel RCTs (n = 70, SMD − 0.77, 95% CI − 1.01 to − 0.52, I 2 = 90%, p = < 0.01)]; participant age groups [paediatric (n = 43, SMD − 0.91, 95% CI − 1.26 to − 0.56, I 2 = 87%, p = < 0.01) vs adults (n = 40, SMD − 0.66, 95% CI − 0.94 to − 0.39, I 2 = 89%, p = < 0.01)] or procedures [venepuncture (n = 32, SMD − 0.99, 95% CI − 1.52 to − 0.46, I 2 = 90%, p = < 0.01) vs childbirth (n = 7, SMD − 0.99, 95% CI − 1.59 to − 0.38, I 2 = 88%, p = < 0.01) vs minimally invasive medical procedures (n = 25, SMD − 0.51, 95% CI − 0.79 to − 0.23, I 2 = 85%, p = < 0.01) vs dressing changes in burn patients (n = 19, SMD − 0.8, 95% CI − 1.16 to − 0.45, I 2 = 87%, p = < 0.01)]. We explored heterogeneity using meta-regression which showed no significant impact of different covariates including crossover trials (p = 0.53), minimally invasive procedures (p = 0.37), and among paediatric participants (p = 0.27). Cumulative meta-analysis showed no change in overall effect estimates with the additional RCTs since 2018.ConclusionsImmersive VR technology offers effective pain control across various medical procedures, albeit statistical heterogeneity. Further research is needed to inform the safe adoption of this technology across different medical disciplines