Rib Wall Research Articles

Predicting the ENS-based SCFs of rib-deck welds by integrating HSS measurement

To improve the efficiency of applying the effective notch stress (ENS) approach in practical engineering, proposing the empirical formula for determining the ENS-based stress concentration factor (SCFENS) by integrating the hot-spot stress (HSS) measurement was the focused in this study. Parametric analysis was conducted to set up the database of the SCFENS and HSS-based SCF (SCFHSS) in presence of different geometric parameters. On this basis, regression analysis was carried out to develop the empirical formulas for predicting the SCFENS, and 2 or 3 reference points-based SCFHSS (i.e., SCFHSS-2 and SCFHSS-3). Furthermore, the additional empirical formula for predicting the SCFENS was developed by considering the SCFHSS-2, SCFHSS-3, and several accessible geometric parameters (i.e., the thickness of the deck plate and rib wall, weld penetration rate, and the angle between the deck plate and rib wall) as the independent variables. Finally, static loading tests of two rib-deck welded specimens were conducted to validate the feasibility and reliability of the proposed formulas. Results show that the formulas for determining the SCFENS, SCFHSS-2, and SCFHSS-3 by geometric parameters of the rib-deck weld, and the formula for determining the SCFENS by the field measurement-based SCFHSS-2 and SCFHSS-3 and several accessible geometric parameters are feasible and reliable. The applicability of the proposed formulas is also validated by a case study. The conclusions are of significant importance to improve the efficiency of applying the ENS approach in laboratory test and practical engineering.

Effects of full internal bulkheads on fatigue behaviors of orthotropic steel decks

To investigate the effects of full internal bulkheads (FIBs) set inside the ribs on the fatigue behaviors of rib-to-floorbeam (RF) details, rib-to-deck (RD) details, and cutout details in orthotropic steel decks (OSDs) and determine whether new fatigue-prone details will be produced, a field monitoring test was conducted, and OSD models with and without FIBs were developed. The study found that in the OSD with FIBs, the stress amplitudes of the RF-F (RF weld on the floorbeam side) and RF-W (RF weld at the rib wall) details were significantly higher than those of the RF-R (RF weld on the rib side) detail, which were more prone to fatigue problems. The FIBs combine the floorbeam with the ribs, which can significantly enhance the in-plane stiffness of the ribs and make the floorbeam function as a solid-web beam rather than a Vierendeel beam. The stress transmission paths at the RF connection are changed by FIBs—particularly at the RF-W and cutout details. The FIBs cause significant improvements at the RF and cutout details but do not affect the stress response of RD details. The RF and cutout details have infinite fatigue life, with the local stiffness enhanced by the FIBs, but the RD details have a finite fatigue life, as the FIBs are far from the RD details. The rib-to-bulkhead (RB) details have the maximum stress at the bottom of the ribs, where the stress outside the rib is higher than that inside, indicating that the fatigue assessment of RB details can be conducted using the stress measured outside the ribs.

Stress Behaviors at Rib-to-Floorbeam Weld and Cutout Details under Controlled Truck Loading

The rib-to-floorbeam (RF) connection is the most complicated joint in orthotropic steel decks (OSDs), where four fatigue-prone details are created, i.e., the RF at the rib side (RF-R), RF at the floor beam side (RF-F), RF at the rib wall (RF-W), as well as the floor beam cutout detail. In order to clarify the behavior of those details under the passage of trucks, a controlled truck loading test and finite element analysis (FEA) are performed at various typical transverse loading locations on a newly built long-span cable-stayed bridge. The research finds that, in the bridge transverse direction, stresses at the four details presented significant local effects. Only when these details are underneath the deck plate covered by the wheel patch a notable stress can be produced at these details. In the bridge longitudinal direction, the wheel loading effect at the four details can be discerned only when the wheels load on the deck supported by their adjacent floor beams. The results find that, under wheel loading, the stress ranges at the RF-R, RF-F and Cutout details are compressive, while the stress at the RF-W detail is in tension. The riding-rib-wall loading is the most critical transverse loading location for the RF and Cutout details, and the RF-W is the most critical fatigue detail in the RF connection. The FEA indicates that, due to offset of wheel loads, floor beams may suffer from severe out-of-plane bending, while ribs may experience notable warping and distortion. Under the passage of the tandem axles, the individual axle cannot be identified, and only one stress cycle is produced at the four details.

Influence of twisted tape with collective protruded rib parameters of thermal–hydraulic performance of [formula omitted] nanofluid flow in heat exchanger tube

Computational fluid dynamics (CFD) is carried out to study the effect of twisted tape (TT) combined with protruded rib and Al2O3-H2O nanofluid on thermal–hydraulic performance in a heat exchanger tube (HET). Influence of twist length and print diameter of protruded rib parameters of heat exchanger tube on heat transfer, pressure drop, and thermal–hydraulic performance are examined. A set of numerical analysis were performed to calculate thermal as well as hydraulic at varying Reynolds number (Ren) ranging from 4000 to 10,000, ratio of twist length to width of twisted tape (Ltwist/Wtwist) ranging from 1.0 to 1.4 and ratio of protruded rib diameter to height of protruded rib (Dpro/Hpro) ranging from 0.50 to 1.25. Other parameters were constant such as relative protruded rib pitch (Ppro/Hpro) value of 5.0, volume concentration (ϕ) value of 6.0 vol% and nanoparticle diameter (dnp) value of 25 nm. The CFD analysis reveals that there is 1.68 and 2.51 times better in the heat transfer and friction factor for twisted tape with combined protruded rib wall HET when it is compared without twisted tape with combined protruded rib wall HET.

On the rotary concentrated solar collector containing twisted ribs and MgO-Ag-water nanofluid

BackgroundIncreasing the solar collectors' performance is of importance to produce higher clean energy. Twisted ribs, having a lengthy background, are beneficial fitted elements to improve mixing between the hot fluid sticking to the absorber with cold fluid flow. MethodThe combination of twisted rib and rotary wall of the tubular solar collector is seeking in the current numerical work. Further, the solar absorber is considered to be filled with a hybrid nanofluid made by water and MgO-Ag nanoparticles. The variations of the average Nusselt number, friction factor, and performance evaluation criteria for all cases are drawn. The power demand of the system to assess the current cost of the new configuration is also calculated. FindingsThe geometry with one twisted rib shows better heat transfer. Adding nanoparticles to the base fluid can improve Nusselt number 18 percent, on average. The increment in the Reynolds number causes 60 to 65 percent higher Nusselt number. The wall rotation has remained either a little aiding or an inverse effect on the heat transfer. However, this makes a lower pressure drop along the solar absorber by demanding low power, as the main advantage.

Experimental and Numerical Investigation of Stress Concentration at Rib-to-Crossbeam Joint

In orthotropic steel decks (OSDs), the rib-to-crossbeam joint is the most vulnerable detail that has not been drawn enough attention. The failure mode of cracks initiate from the lower weld end on rib wall is governing its fatigue performance. However, relevant detail categories are still missing in prevailing codes. This paper mainly focuses on the stress concentrations at the rib-to-crossbeam joint induced by rib distortions. A series of static load tests were first performed on a full-scale OSD specimen with different weld length between the ribs and the crossbeam. Then, corresponding numerical simulations were finished. Several possibilities that may cause the differences between the measurements and the calculations are investigated. At last, fatigue assessments based on influence lines of structural hot spot stress (SHSS) are completed. Research results reveal that the measurement results of reference points for SHSS method would be very sensitive to the exact location of strain gauges. Due to the manual welding, the deviation of strain gauge positions induced by the irregular weld shape is thought to be the main reason that causes the differences between measurements and calculations. Raising the location of cope hole terminations would decrease distortional stresses. However, the influence of this parameter on fatigue lives is rather small. The fatigue lives of points along the lower weld toe are very close. Hence, the point at the middle plane of crossbeam could be used as the reference point for fatigue assessments. Meanwhile, the center between ribs could be used as the reference transverse load position for fatigue assessments of this joint.

Investigating Liquid Water Transport in Different Pore Structure of Gas Diffusion Layers for PEMFC Using Lattice Boltzmann Method

Proton exchange membrane fuel cells (PEMFC) require a gas diffusion layer (GDL) and micro porous layer (MPL) to aid in the transport of liquid fuel to the catalyst layer. The GDL needs to remain saturated to assist in the chemical reaction at the catalyst layer. The mass transport through the gas diffusion media is essential to the operation of the PEMFC system. Previously, to observe the liquid flow through gas diffusion media, X-ray CT scans were used. X-ray CT scans have limitations in the resolution capability. When applying a microporous layer to a GDL sample, X-ray CT’s have difficulties capturing the saturation at the micro scale level. In this work, direct modeling using the Lattice Boltzmann Method (LBM) [1-3] was applied to micro X-ray CT scans of commercial carbon paper gas diffusion media geometries. The LBM, combined with computational fluid dynamic modeling techniques, can accurately predict liquid saturation at the macro and micro scale, which provides more insight into the mass transport phenomena through the GDL. Three injection cases, seen in Figure 1, were investigated using different samples. The rib and channel wall boundary were created to represent the effect of the flow-field area inside the PEMFC. Liquid water flow through samples with and without MPL’s were studied. The primary focus of this work is to understand the transport of liquid water through the gas diffusion media, determine which injection case results in the most liquid saturation, and if the addition of an MPL increases or decreases saturation levels inside the GDL. Figure 2 shows an example of the predictions of water evolution inside sample EP40-T, without the addition of a MPL. The sample was ran at all three injection cases. When comparing each case, a dual injection point with a land and channel orientation, case 3, resulted in the most liquid present inside the sample. This work will be extended to include the effect of non-uniform wettability of GDL on water transport and saturation.

A Powerful Build-Up Rate (BUR) Prediction Method for the Static Push-the-Bit Rotary Steerable System (RSS)

The RSS has been widely used in directional drilling. In order to enhance wellpath control accuracy and efficiency of the static push-the-bit RSS, a powerful BUR prediction method is reconstructed by coupling a rotary steerable bottom-hole assembly (RSBHA) mechanical model and a drill bit–rock interaction model. This article showed that when establishing the RSBHA mechanical model by using the continuous beam column method, the steering rib should be treated as an eccentric stabilizer to consider the contact effect between the steering rib and wellbore wall. For the beam column containing the flexible sub and between two stabilizers, it should be rearranged into three beam columns, and the lower and upper steps of the flexible sub should be considered as virtual supports. The equilibrium tendency method (ETM) to predict the BUR can enhance wellpath prediction accuracy than those of traditional methods. Under 3D conditions, the total drilling tendency angle should be denoted by inclination tendency angle and azimuth tendency angle to enhance the solution efficiency. Case analyses have verified that the average forecast error of the BUR prediction model in this article is less than 1°/30 m.

Turbulence characteristics over k-type rib roughened porous walls

To understand the permeability effects on turbulent rib-roughened porous channel flows, particle image velocimetry measurements are performed at the bulk Reynolds number of 5000–20000. Solid impermeable and porous ribs are considered for the rib-roughness whose geometry is categorised in the k-type roughness whose pitch/rib-height is 10. Three isotropic porous media with nearly the same porosity: 0.8, and different permeabilities (0.004, 0.020, 0.033 mm2) are applied. It is observed that the recirculation between the ribs becomes weak and the recirculation vortex submerges into the porous wall as the wall permeability and Reynolds number increase for both solid and porous rib cases while the recirculation vanishes in high permeable cases. These phenomena result in characteristic difference in turbulence quantities. By fitting the mean velocity profiles to the log-law form, the permeability effects of both rib and bottom wall on the log-law parameters and the equivalent sand-grain roughness are discussed. It is concluded that the zero-plane displacement increases while the von Kármán constant and the equivalent sand-grain roughness decrease as the wall and rib permeability increases.

Fatigue behavior of orthotropic bridge decks with two types of cutout geometry based on field monitoring and FEM analysis

This paper provides comparative results on stress behavior and fatigue performance of two types of cutout geometry on orthotropic bridge decks based on simultaneous field monitoring and finite-element method (FEM) analysis. The two types of cutout are incorporated in two closely spaced diaphragms with distance of 6 m and at the same transverse location on a real bridge, allowing simultaneous stress measurement under random traffic flows. The research was conducted on the Pingsheng Bridge in Southern China, a self-anchored suspension bridge with a main span of 350 m and a steel box girder with orthotropic steel bridge decks (OSBD). Results of the study reveal that the two types of cutout geometry present high stress response and severe stress concentration at the floorbeam (FB) cutout, and that the excessively large stress at the original FB cutout contributes greatly to the early cracks of this detail. Compared to the original cutout geometry, the new cutout geometry with large radius increases the stress level at the FB cutout, resulting in a further low fatigue life at this detail. Meanwhile, the new cutout geometry also deteriorates the fatigue resistance at the rib-to-floorbeam (RF) weld connection, particularly at the detail of rib wall at cutout, where the stress level is significantly increased and its fatigue life becomes substantially lower than the design life of 100 years. In addition, the new cutout geometry only slightly improves the out-of-plane distortion under direct wheel loading, and the in-plane stress still dominates the total stress at the FB cutout. Since the new cutout geometry weakens the FB web, the total stress at FB cutout will increase due to the increased in-plane stress. The research also finds that if the free edge of cutout did not satisfy the fabrication requirement per the AASHTO LRFD, category B is suggested for fatigue evaluation at the FB cutout, which is confirmed by the observed fatigue life of the original FB cutout on the real bridge. It is concluded that the new cutout geometry lowers the fatigue resistance both at the FB cutout and at the RF weld connection, hence it will no longer be recommended to retrofit the present bridge in the future.

Experimental Study of the Influence of the Shape of the Gap between the Rib and Flat Plate on the Near-Wall Flow Structure and Heat Transfer

The article presents an analysis of the results of an experimental study of the dynamic and thermal characteristics of the turbulent boundary layer of the air near a heated plate at qw = const with rectangular ribs having slit channels of different geometry: confusor, diffuser, and plane-parallel. The slit channel is located between the plate and the lower rib wall. The results are compared with similar data for a solid rib without the slit channel. A Pitot–Prandtl microprobe with a microthermocouple and the Dantec Dynamics hot-wire anemometer were used, thus making it possible to study the laminar sublayer, the transition domain, and the outer part of the boundary layer. The influence of the slit profile on the average and the pulsation characteristics of the turbulent dynamic and thermal boundary layers in the median section of the plate with the slit rib is revealed. It is found that the separated zone disappears in the flow behind the ribs with the confusor slit.

Fatigue behavior of orthotropic steel bridge stiffened with ultra-high performance concrete layer

As a novel cement based material, the ultra-high performance concrete (UHPC) has been recently used in reinforcing steel bridge decks. In this paper, an orthotropic steel bridge (OSB) stiffened with UHPC layer is modeled via the finite element submodel technique. The stress responses of fatigue-prone details under wheel loads are obtained, and the fatigue performance is also evaluated. The stress tendencies observed by the finite element models are compared to the stress response data from field measurements. It is observed that an application of 45 mm thick UHPC layer on the OSB deck can reduce the stress range at deck side of rib-to-deck (RD) joint by up to 70.9%, achieving an infinite fatigue life. However, the stress ranges for the other three details are still significant, including the stress range at rib side of RD joint (with both membrane and bending stresses), the stress range on rib wall at weld end of rib-to-floorbeam (RF) joint (with both rotational and Poisson's effects), and the stress range at floorbeam side of RF joint (due to the in-plane deformation and out-of-plane twist). To reduce such significant stress ranges in achieving infinite fatigue life of the bridge under high traffic volume, the critical influencing parameters on the stress ranges are studied and selected for fatigue design.

Effect of rough inner wall of nanochannel on fluid flow behavior

Flow system on a nano scale, as an effective and economic system, has been widely employed. While on a macroscopic scale, for the non-slip boundary, the velocity of the fluid at the surface is assumed to be consistent with the surface. This approximation may become invalid on a smaller length scale pertinent to the operation of microfluid devices. The interface slip effect has a significant influence on the flow because of its higher ratio of surface to volume. In this paper, the Poiseuille flow, which is composed of two infinite parallel asymmetric walls, is studied by the molecular dynamics method. The influence of wall roughness and surface wettability of channel on fluid flow in the channel are analyzed. The results show that the asymmetric upper and lower wall can lead to an asymmetric distribution of flow parameters. The change of wall roughness and wettability would affect the flow characteristics of fluid atoms near the wall. Due to the influence of wall grooves, the number density distribution near the rough wall is lower than that on the smooth wall side. As the rib height and wall wettability increase, the number density of fluid atoms in the groove increases gradually, and the change of the rib spacing does not substantially affect the number density distribution of fluid atoms near the rough wall. For different structure types of walls, the real solid-liquid boundary positions are determined by simulating the velocity field distribution in the channel under both Couette flow and Poiseuille flow, which can help us to better analyze the interface slip effect. The variation of wall roughness and wettability can affect the position of the solid-liquid interface. The change of rib height and wettability can greatly influence the velocity distribution in channel, and the position of the solid-liquid boundary as well. Conversely, the rib spacing has a less effect on the boundary position. The difference in boundary position can affect the interface slip effect. We can find the slip velocity and the slip length on one side of the rough wall to be smaller than those on the smooth wall side, and as the rib height and wall wettability increase, the slip velocity and the slip length significantly decrease near the rough wall side. The effect of rib spacing on fluid flow is trivial, and the interface slip velocity and length are relatively stable.

Heat Transfer and Flow Characteristics of Two-Pass Parallelogram Channels With Attached and Detached Transverse Ribs

The full-field Nusselt number (Nu) distributions and flow fields are presented, respectively, using steady-state infrared thermography (IR) and particle image velocimetry (PIV) in the two-pass parallelogram channels with attached and detached transverse ribs. These square transverse ribs on two opposite channel walls are in-line arranged with rib-height to duct-height ratio of 0.1 and rib pitch-to-height ratio of 10. For the detached ribs, the detached distance between rib and channel wall is 0.38 rib height. With the measurements of Fanning friction factor (f), the thermal performance factors (TPF) for the attached and detached-rib cases are comparatively examined. A set of Nu, f, and TPF with the associated flow measurements at the Reynolds number range of 5000 ≤ Re ≤ 20,000 is selected to disclose the differential heat transfer mechanisms and efficiencies between the attached and detached ribbed channels. Empirical correlations evaluating the area-averaged Nusselt numbers (Nu¯) and f factors are devised to assist the relevant design activities.

Dosimetric variations in permanent breast seed implant due to patient arm position.

Planning and delivery for permanent breast seed implant (PBSI) are performed with the ipsilateral arm raised; however, changes in implant geometry can be expected because of healing and anatomical motion as the patient resumes her daily activities. The purpose of this study is to quantify the effect of ipsilateral arm position on postplan dosimetry. Twelve patients treated at the Tom Baker Cancer Centre were included in this study. Patients underwent two postimplant CT scans on the day of implant (Day 0) and two scans approximately 8 weeks later (Day 60). One scan at each time was taken with the ipsilateral arm raised, recreating the planning scan position, and the other with both arms down in a relaxed position beside the body, recreating a more realistic postimplant arm position. Postplans were completed on all four scans using deformable image registration (MIM Maestro). On the Day 0 scan, the V200 for the evaluation planning target volume was significantly increased in the arm-down position compared with the arm-up position. Lung, rib, and chest wall dose were significantly reduced at both time points. Left anterior descending coronary artery, heart, and skin dose showed no significant differences at either time point. Although some dosimetric indices show significant differences between the arm-up and arm-down positions, the magnitude of these differences is small and the values remain indicative of implant quality. Despite the delivery of the majority of dose with the arm down, it is reasonable to use CT scans taken in the arm-up position for postplanning.

Factores que influyen en la sobrevida y pronóstico de pacientes con cáncer de mama invasor operable.

Este estudio retrospectivo evaluó factores clínico patológicos relacionados con la sobrevida y la recurrencia de 54 pacientes con cáncer de mama estadios clínicos I y II, tratadas con mastectomía Halsted en el Hospital Belén (Trujillo Perú), entre enero 1966y diciembre 1982. Con fecha diciembre de 1992, el periodo de seguimiento medio fue de 165,2 meses para las 28 pacientes sobrevivientes (rango 125 a 288 meses). La sobrevida global a 10 años fue de 52,8%. La incidencia de recurrencia local fue de 20,4% y el tiempo medio de su aparición fue 32,6 meses. Del 18,5% con recurrencia en la pared costal, ninguna paciente sobrevivió más de 10 años después de su aparición, Diecinueve casos (35,2%) desarrollaron metástasis a distancia, siendo las más frecuentes a pulmón y ganglios. Nuestros hallazgos indicaron que la edad, el tiempo de enfermedad, el estado menopáusico y la localización del tumor no influenciaron en el pronóstico. La sobrevida global y la recurrencia local o distante estuvieron significativamente correlacionadas con el tamaño tumoral y el estadio clínico. Hubo relación inversa significativa entre el número de ganglios axilares positivos y la sobrevida global (p<0,05). El nivel axilar comprometido no tuvo valor significativo. Concluimos que el tamaño tumoral, el estadio clínico y el número de ganglios axilares comprometidos son factores pronósticos correlacionados con la sobrevida y el relapso en pacientes con cáncer de mama invasor operables y las estrategias de tratamiento deben estar basadas en la comprensión clara de estos factores.

Fatigue Crack Behavior at Rib-To-Deck Weld Bead in Orthotropic Steel Deck

One of the typical fatigue cracks observed in orthotropic steel deck is a through-thickness crack which penetrates and propagates along the weld bead. Moreover, according to some reports of the fatigue crack observed in some bridges, the fatigue crack sometimes changes its direction suddenly, and propagates to the rib wall and the deck plate. Such fatigue damage can cause the sudden decrease of stiffness of longitudinal rib. However, the propagation mechanism of the crack has not been investigated clearly. In this study, numerical studies on the through-thickness crack at rib-to-deck weld bead in the orthotropic steel deck were carried out. Finite element model (FEM) of an orthotropic deck with different through-thickness crack at rib-to-deck weld bead was created. In order to identify the propagation behavior of the fatigue crack, stress intensity factors for three deformation modes were estimated by the FE analysis (FEA) and the displacement extrapolation method. Based on the maximum energy release rate (MERR) criterion, the equivalent stress intensity factor and the crack direction were evaluated. From the numerical results, the crack direction change was found to be originated by the Mode II and Mode III deformation near the crack tip due to the out-of-plane bending of the rib wall along the crack.

Weight reduction of a standard brake drum: A design approach

A Brake drum is specialized brake that uses the concept of friction to decelerate the vehicle speed. The deceleration is achieved by the assistance of the friction generated by a set of brake shoes or pad, when operator presses against a rotating brake drum. The material generally preferred for making the brake drum is grey cast iron or vermicular cast iron. The drum brake is highly efficient for hand brake and service brake applications. During the operation of drum brake excessive heating of brake drum may occur. This excessive heating occurs due to repeated or frequent contact of the brake shoes against the drum. This causes the drum to crack, oversize, extreme wear, out of round drums and also leads to vibration which while braking will leads to reduced brake drum life and braking efficiency. The Un-laden weight of the vehicle will result in increased fuel consumption, reduced payload and ride handling characteristics. The objective of the paper is to improve the thermal characteristics by incorporating fins in the brake drum and to reduce the un-laden weight of the vehicle by changing the rib thickness, wall thickness and base flange thickness. The design is done by using 3D CAD Modelling software and Hexahedral finite element model prepared by using CAE pre-processing software and Stiffness analysis. Design iterations are carried out by using Linear/Non-linear Finite Element Solvers, Stress Displacement and Temperature is post-processed for design validation. Optimized design solution obtained based on the comparison study between the iteration with rib thickness 75 mm, star shaped removal and wall thickness 17 mm has been chosen. 1.8Kg of weight is being reduced from the brake drum including fins. Keywords: Drum Brake, 3D CAD Modelling, Para Metric Matrix, Structural Analysis, Fins.

Positional footprint characterisation of truck tyres on flexible orthotropic steel bridge decks

Vehicular tyre tread and footprint characteristics have been investigated from the point of view of tyre design and manufacturing and dynamic vehicle analysis, as well as for pavement design and analysis. From these analyses, it has become clear that typical commercial truck tyres do not exhibit a uniform pressure over the footprint area. Instead, a highly non-uniform pressure distribution is observed depending on tyre type, internal pressure, axle load, etc. Nevertheless, such analyses are generally related to rigid driving surfaces, but commercial vehicles also frequently cross bridges, where the driving surface is much more flexible. Indeed, the flexibility of a steel deck will change the footprint characteristics due to the adaptation of the contact surface to the presence of more and less rigid areas. In this paper, the pressure distribution under a truck tyre when crossing a bridge with a steel orthotropic bridge deck is investigated. The contact pressure is measured by an 8.4 mm-resolution pressure mat in between a common widebase tyre and an orthotropic bridge deck test specimen. Comparisons are made with existing literature for rigid surfaces, especially the analyses of R Blab at Berkeley, in order to investigate the influence of the tyre pressure, total applied load and the transverse position relative to the rib walls on the pressure distribution. The results indicate that the transverse positioning does indeed affect the pressure distribution, as the stiffer rib wall attracts a larger part of the load. Consequently, uniform pressure loads overestimate plate bending for loads in between the rib walls and underestimate plate bending for loads over the rib walls. In this way, the detailed non-destructive pressure distribution analysis has contributed to a better understanding of failure analysis, especially at the rib-to-deckplate connection, of steel bridge decks.

Scoliosis after chest wall resection

There has been an increased focus on the role of rib abnormalities in the development of scoliosis. Rib resection may influence the development of scoliosis. Although scoliosis has been identified in patients after thoracotomy, most of the currently available information is from case reports. We examined records of 37 patients who underwent a chest wall or rib resection for rib lesions at our institution during the period of 1992 to 2005. Adequate data was available in 21 patients. We gathered data on demographic information, location of resection, and changes in curvature after resection based on radiograph or scout CT films at the latest follow-up appointment. Fourteen of 21 patients developed scoliosis with a mean Cobb angle of 25.8° (10°-70°). Eleven of these 14 patients had a progressive spinal deformity after chest wall resection with an average change in curvature of 29° (10°-70°). Eight of those 11 developed a convex toward the resection, while 3/11 developed a convex away from the resection. Seven of the eight patients with resections that included a rib superior to the sixth rib developed scoliosis, while four of 13 with resections below the sixth rib developed scoliosis. Patients who have had a rib or chest wall resection are at risk for developing scoliosis, particularly if the resection is performed above the sixth rib.