Unequal Height Research Articles

Structural behavior of double-CFT-pile foundations under cyclic loads

This paper presents experimental and analytical studies on the structural behavior of double-pile foundations under cyclic loads. Three large-scale pile foundation specimens with vertical or battered concrete filled steel tube (CFT) piles plainly embedded into concrete caps were tested. The effects of embedment depths, inclination angles and unequal heights of the CFT piles on the failure modes, strength, lateral stiffness, ductility and energy dissipation capacity were evaluated. The experimental and analytical results indicate the pile diameter embedment is adequate for forming the plastic hinge at the ends of both vertical and battered CFT piles. However, block shear failure and pry-out of the concrete caps inhibited the complete development of the plastic hinges at CFT pile ends. The use of battered piles significantly increases the loading capacity, lateral stiffness and energy dissipation capacity of pile foundations, but decays the deformation capacity and ductility of pile foundations. The unequal heights of battered CFT piles increase the shear and axial loads carried by the short pile, resulting in the potential premature failure of the short pile. The total lateral loading capacity of the pile foundation is not significantly affected by the unequal heights; however, the deformation capacity of the foundation decreases with increase of the unequal height ratios.

Study and Analysis of Pounding Effect between Adjacent RC Buildings

Pounding occurs when the adjacent buildings start vibration out of phase during the seismic activity which causes the collision between the adjacent structures. Due to higher cost of land in cities people have tendency to attach the buildings at property line. Earthquakes can cause pounding when adjacent buildings have little gap or no gap providing separation. Due to pounding effect structural and non – structural damage may occur in the adjacent buildings.
 The main objective of this research is to assess the seismic response of common residential RC buildings that has been constructed with no gap with the adjacent structures and to find the minimum gap requirement for the commonly constructed buildings of Nepal.
 For this study two different cases with varying separation distance between adjacent buildings have been considered. First case is the adjacent buildings having equal storey height but different number of stories. It includes models having 4 and 2 stories and 4 and 3 stories. Second case is the adjacent buildings having unequal storey height but same number of stories. It includes models having 3 and 3 stories and 4 and 4 stories. In both cases adjacent buildings have same material & sectional properties. Non-linear dynamic analysis is performed using El-centro earthquake data as ground motion. Gap element has been used to simulate the pounding force between buildings. Adjacent buildings having different overall height are modelled in SAP 2000 v 15 using gap element for pounding study. The seismic responses in terms of joint displacement, joint acceleration, pounding force are presented. Joint displacement and joint acceleration comparison for both pounding and no pounding cases are presented.
 Gap calculation from NBC and IS code, ABS and SRSS method was compared with gap required to avoid pounding force between adjacent structures and appropriate gap was recommended.

Performance assessment of bridge-soil-foundation system with irregular configuration considering ground motion directionality effects

Highway bridges with piers of unequal height crossing irregular topographical surfaces have potential complexities in terms of component vulnerability evaluations. This paper investigates the seismic behavior of a five-span concrete girder bridge with three coefficients of pier height and two different types of irregular configurations. Moreover, soil-structure interaction is taken into account by modeling a typical deep foundation, including piles and the surrounding soil, in order to examine the effect of pier base flexibility compared to the equivalent fixed-base model. For this purpose, incremental dynamic analyses are performed on the three-dimensional analytical finite element models using a set of ground motion pairs each rotated about the vertical axis of bridge producing seven angles of seismic incidence. The results obtained from the dynamic analyses and fragility assessment of the selected bridge models illustrate that substructure irregularity, support condition of piers, and directionality of seismic excitations are three interdependent factors in vulnerability assessment of highway bridges. Variation in each of the above-mentioned factors leads to change in the fragility characteristics of a bridge at global system failure mode or individual component limit states.

RIGHT UNILATERAL PULMONARY APLASIA

SESSION TITLE: Lung Pathology 2 SESSION TYPE: Fellow Case Report Posters PRESENTED ON: 10/09/2018 01:15 PM - 02:15 PM INTRODUCTION: Pulmonary agenesis is an extremely rare congenital abnormality. There is incomplete development of lung due to embryological defects. This condition is diagnosed in neonates presenting with respiratory distress. CASE PRESENTATION: A 24 year old male, asymptomatic, consulted for pre-employment clearance. Mother had episode of vaginal bleeding on 5th month of gestation but patient was carried to full term with uneventful birth history. Patient was noted frail growing up, with recurrent pulmonary infection. There was noted shallowness of right nasolabial fold, unequal shoulder height. Right hypothenar was atrophied. Trachea was shifted to the right. There was lag on right chest wall and absence of breath sounds on right lung. Chest xray showed full opacification of the right hemithorax with tracheal deviation to the right. Chest CT scan showed absence of right lung and supplying vasculature. Mediastinum was noted occupying the right hemithorax. Diagnosis was right pulmonary aplasia. DISCUSSION: Pulmonary agenesis encompasses undeveloped pulmonary parenchyma, pulmonary vasculatures, and airways. There is failure of development of the primitive lung bud. Arrest in the development of respiratory system from the foregut corresponds to these embrogenic malformations. Respiratory anlage may develop unilaterally leading to lung agenesis. Unilateral aplasia and hypoplasia are better viable with life. Functionally, unilateral agenesis and aplasia are similar. Sole functional lung is larger than normal to compensate and this enlargement is true hypertrophy and not emphysema.Primary causes include deficiency in TTF-1, HNF310, and EGFR. Secondary causes include small fetal thoracic volume, prolonged oligohydramnios, and congenital heart diseases. A third diagnosed during adulthood are asymptomatic. Recurrent childhood respiratory infections are common symptoms leading to identification. Diagnosis is suspected in patients examined with tracheal deviation, in the presence of a clinically symmetric chest and massive atelectasis in chest xray. Chest CT scan has emerged as diagnostic modality of choice in diagnosis. There is no treatment needed for asymptomatic cases. Treatment is necessary in the presence of respiratory tract infections. Prognosis of pulmonary aplasia depends on severity of co-existing congenital malformations and involvement of normal lung in infection and large vessels kink due to mediastinal displacement. Normal life span is expected for those surpassing first five years without major infection.There is higher mortality with right lung agenesis than left due to greater compression of tracheobronchial tree by shifting of midthoracic structures into the right chest. CONCLUSIONS: Pulmonary aplasia is a rare congenital abnormality characterized by absence of lung parenchyma and supporting vasculature. Patients with no other concomitant congenital anomaly survive well into adulthood. Reference #1: Mardini M K, Nyhan W L. Agenesis of lung: Report of 4 patients with unusual anomalies. Chest 1983; 87:522-7. Reference #2: Conway K, Gibson RL, Perkins J, Cunningham ML. Pulmonary agenesis: Expansion of the VCFS phenotype. Am J Med Genet. 2002:11389–92. Reference #3: Richard S. Synopsis of Diseases of the Chest. 2nd ed. Phildelphia: W. B. Saunders Company; 1994. Pulmonary Abnormalities of Developmental Origin; p. 25686. DISCLOSURES: No relevant relationships by Portia Maria Tanyag, source=Web Response

Research and Experiment on Optimal Separation Distance of Adjacent Buildings Based on Performance

Firstly, constitutive models of two unequal height adjacent ten-story and six-story reinforced concrete frame structures were established based on OpenSees software in which a series of separation distances are set for incremental dynamic analysis (IDA), respectively. Secondly, the seismic vulnerability curves by postprocessing programming in Matlab software were obtained based on IDA datum, and the optimal separation distances of adjacent buildings with and without connecting dampers were obtained by comparing the seismic vulnerability of adjacent building at different separation distance and the seismic hazard analysis. Finally, a scaled model shaking table test of adjacent steel frame structures was performed. The conclusions are obtained by comparing the measured results of the test with those obtained by the OpenSees analysis, such as acceleration and displacement. The conclusions show that when two adjacent buildings are not connected with a damper, the distance of adjacent structures is suggested to be 0.3 m under moderate and strong earthquakes and the distance of adjacent structures is suggested to be a specified value of 0.24 m under rare earthquakes. When two adjacent buildings are connected with dampers, the separation distance is suggested to be 0.1 m under various performance conditions.

Overhead Accumulative Sliding Construction Technology of Unequal Height of Large Span Spatial Steel

The large span spatial steel was used in chop manufactory of the Chengdu integrated circuit manufacturing project. Because the steel truss was of great importance and the span of the single one was large, the crane was difficult to cover the aerial platform. Overhead accumulative slip construction scheme was based on construction conditions of engineering site. This paper introduced construction process of slippage of unequal height and the selection of equipment and preparatory work before sliding. At the same time, in view of the special unequal height support of the project, the heavy and difficult points of construction were analyzed. The state of the structure in the sliding process and the possible adverse effects on the slip were analyzed in detail, and some suggestions were put forward. To ensure the safety and reliability of the slip construction scheme, the bending, synchronism and the stress of key member of the structure were monitored during the sliding process.

Effects of Irregular Bridge Columns and Feasibility of Seismic Regularity

Bridges with unequal column height is one of the main irregularities in bridge design particularly while negotiating steep valleys, making the bridges vulnerable to seismic action. The desirable behaviour of bridge columns towards seismic loading is that, they should perform in a regular fashion, i.e. the capacity of each column should be utilized evenly. But, this type of behaviour is often missing when the column heights are unequal along the length of the bridge, allowing short columns to bear the maximum lateral load. In the present study, the effects of unequal column height on the global seismic performance of bridges are studied using pushover analysis. Codes such as CalTrans (Engineering service center, earthquake engineering branch, 2013) and EC-8 (EN 1998-2: design of structures for earthquake resistance. Part 2: bridges, European Committee for Standardization, Brussels, 2005) suggests seismic regularity criterion for achieving regular seismic performance level at all the bridge columns. The feasibility of adopting these seismic regularity criterions along with those mentioned in literatures will be assessed for bridges designed as per the Indian Standards in the present study.

Seismic Response of Adjacent Unequal Buildings Subjected to Double Pounding Considering Soil-Structure Interaction

Various cases of two adjacent multi-story buildings with different numbers of floors and equal or unequal foundation levels under earthquake loading and considering soil-structure interaction (SSI) are investigated. A two-dimensional model for each case of the two adjacent unequal buildings without separation distance is used and a special arrangement of contact elements in the contact zone is employed to fulfil all possible deformation contact modes which take place under seismic loading. The soil is modelled by two-dimensional 4-node elements which are in contact with the foundations of the two adjacent buildings. This paper studies the earthquake-induced double pounding that takes place between the two adjacent unequal height buildings in some upper points at superstructure in the contact zone and also at foundation level, considering soil-structure interaction (SSI). The double pounding and the soil-structure interaction (SSI) effects should be taken into consideration in the seismic analysis of adjacent buildings especially those with different heights and different foundation levels.

Investigation of the effect of the sling angle and size on the reliability of lifting hooks

The lifting hook is one of the vital components in material handling systems, since sudden accidents are unavoidable if the working reliability of the hook is poor. In this study, computer-aided single hook modeling is done in accordance with the DIN 15401 standard then extensive stress analyses at different sling sizes and angles and stress analyses when the hook is rigged by sling legs with unequal leg length and rigged by sling legs with unequal leg length and height have been conducted in order to reveal the effect of sling size and angle and different rigging manners on the safety factor of the lifting hook by using finite element simulation. Loads carried by each sling member are calculated and presented. Curved beam theory and simplified theory are employed to compare finite element simulation results. The critical sling angle at which the safety factor reduces evidently has been determined by altering the sling size and angle. The critical sling angle is found to be 51°, since reduction in the safety factor originates from a 51° sling angle.

Effects of SSI on seismic responses of unequal height pier bridge

Based on the secondary development of LS-DYNA program, the nonlinear dynamic p-y model and Bonora damage material model of steel were applied in the main program. Taking a four-span approach bridge as an example, the plastic damage model of the upper bridge and four simplified bridge pile-foundation models, including beam on Winkler foundation model, effective length pile model, total pile model considering soil-structure interaction (SSI) and no pile model, were introduced. The earthquake motions obtained by a free-field analysis were applied to the different depth of pile profile. The free vibration characteristics, displacement, internal force and damage under different levels of earthquake motions were analyzed. The stress-strain curve of different depth of p-y elements and pile deflection of Winkler-methods model were discussed. Analysis results indicated that the structure responses are different among the four pile-foundation models, the responses of the bridge in longitudinal and transverse directions are totally different, and the p-y model can be used to simulate the bridge precisely.

Energy Absorption and Crush Behavior of the Layered Aluminum Honeycomb

To investigate the energy absorption characteristics and crush behavior of layered aluminum honeycomb, the experiments of layered aluminum honeycomb structure under quasi-static load had been carried out, mainly includes single, double, triple, four layer combinations. The results showed that: the peak force and the mean plateau force of single-layer aluminum honeycomb structure are proportional to the surface density, however they decline slightly with increase of the height; unequal height double layered aluminum honeycomb structure has more advantage in cushion performance; with the increase of layers, the MP ratio will decrease; the combination of placing soft layer between hard layers is better than the others.

Laser metal deposition with spatial variable orientation based on hollow-laser beam with internal powder feeding technology

In this study, a hollow-laser beam with internal powder feeding (HLB-IPF) head is applied to achieve non-horizontal cladding and deposition of overhanging structure. With the features of this head such as uniform scan energy distribution, thin and straight spraying of the powder beam, the deposition in spatial variable orientation is conducted using a 6-axis robot. During the deposition process the head keeps tangential to the growth direction of the part. In the experiment, a “vase” shaped metal part with overhanging structure is successfully deposited, and the largest overhanging angle achieves 80° to the vertical direction. The “step effect” between cladding layers is completely eliminated with the best surface roughness of Ra=3.864µm. Cross section of cladding layers with unequal height are deposited for angle change. Test results indicate that the formed part has uniform wall thickness, fine microstructure and high microhardness.

Modes competition in superradiant emission from an inverted sub-wavelength thick slab of two-level atoms

Using the expansion in the eigenmodes of 1-D Lienard-Wiechert kernel, the temporal and spectral profiles of the radiation emitted by a fully inverted collection of two-level atoms in a sub-wavelength slab geometry are computed. The initial number of amplifying modes determine the specific regime of radiation. In particular, the temporal profile of the field intensity is oscillatory and the spectral profile is non-Lorentzian with two unequal height peaks in a narrow band centered at the slab thickness value at which the real parts of the lowest order odd and even eigenvalues are equal.

Do mixed pier-to-deck connections alleviate irregularity of seismic response of bridges with unequal height piers?

Uniformity in seismic response of apparently irregular bridges has been an intensive topic of research. EuroCode proposes a force-based criterion that indicates whether such bridges under seismic ground motion are considered uniform or not. In this research, several case study three-span bridges with unequal pier heights and different pier-to-deck connection configurations are designed as per EC8 requirements for irregular bridges, then investigated for (a) seismic response uniformity up to collapse limit state, (b) intrinsic overstrength, and (c) material usage efficiency under inelastic static pushover as well as incremental dynamic analysis using a bin of seven real earthquakes. Design optimization targeting regular response is performed on each bridge scheme based on an enhanced curvature-based uniformity criterion, and the results are compared to the initial design complying with EuroCode requirements. Among the main conclusions of the current research is that irregular bridges under investigation complying with EuroCode uniformity index do not necessarily behave in a uniform manner under seismic loading. Response uniformity has been improved drastically by altering the steel reinforcement ratios of either the short or the long pier and/or by changing the types of pier-to-deck connection. Associated changes in the inherent overstrength of each scheme as well as the usage efficiency of piers reinforcement are also monitored and compared to the initial design. The current investigation hence emphasizes that it is the designer’s role to accentuate and delineate the main aspects of the design requirement of irregular bridges: either heading towards better uniformity in response and/or improved built-in overstrength, or targeting a more economically efficient design in terms of piers reinforcement ratio but with reduced, yet satisfactory, uniformity. All these aspects could however be more-or-less mutually accomplished but with certain limitations.

Seismic Fragility Assessment of Skewed MSSS-I Girder Concrete Bridges with Unequal Height Columns

Multi Span Simply Supported Bridges (MSSS) are categorized among the most vulnerable bridge classes and their vulnerability increases when different sources of irregularities such as skewness as well as columns height differences are included. Different sources of irregularities make the irregular bridge more complicated in case of dynamic response than regular bridges, and therefore a comprehensive study should be implemented to explore the effect of different irregularities on seismic performance of bridges individually and jointly. This paper explores the effect of skewness and unequal height columns on the seismic response of MSSS-I girder concrete bridges commonly constructed in Central and Southeastern United States (CSUS). The scope of the study is limited to tree spans which are the most prevalent spans in this class of bridges. The results show that the component fragilities become more sensitive to column height ratio with increase in the bridge skew angle particularly in longitudinal direction. The study of the combined effects of skewness and column height ratio on the bridge system fragility also reveals that the column height ratio has negative effect on the fragility of bridge system in all damage states and different skew angles but this effect increases by increasing the skewness as well as damage state of interest.

A comparative study on the material removal mechanisms of 6H-SiC polished by semi-fixed and fixed diamond abrasive tools

Comparative experiments involving processing SiC substrates with the semi-fixed and the fixed diamond abrasive polishing tool have been conducted in this study. The material removal mechanisms of SiC substrates are investigated by the surface topography of substrate, the wear appearance of abrasives in tools and the analysis of wear debris. The results indicate that the removal scale of diamond grits in the fixed abrasive polishing film is much larger because of the higher abrasive protrusion heights. Moreover, the unequal protrusion height of diamond abrasives can also easily create deep scratches and damages on the substrate surface. However, the removal scale of diamond grits in the semi-fixed abrasive polishing film is smaller due to the effect of abrasive yielding. The obtained smooth and scratch-free surface with nanoscale roughness can shorten the total processing time and cut the cost.

Seismic Evaluation of a Multitower Connected Building by Using Three Software Programs with Experimental Verification

Shanghai International Design Center (SHIDC) is a hybrid structure of steel frame and reinforced concrete core tube (SF-RCC). It is a building of unequal height two-tower system and the story lateral stiffness of two towers is different, which may result in the torsion effect. To fully evaluate structural behaviors of SHIDC under earthquakes, NosaCAD, ABAQUS, and Perform-3D, which are widely applied for nonlinear structure analysis, were used to perform elastoplastic time history analyses. Numerical results were compared with those of shake table testing. NosaCAD has function modules for transforming the nonlinear analysis model to Perform-3D and ABAQUS. These models were used in ABAQUS or Perform-3D directly. With the model transformation, seismic performances of SHIDC were fully investigated. Analyses have shown that the maximum interstory drift can satisfy the limits specified in Chinese code and the failure sequence of structural members was reasonable. It meant that the earthquake input energy can be well dissipated. The structure keeps in an undamaged state under frequent earthquakes and it does not collapse under rare earthquakes; therefore, the seismic design target is satisfied. The integrated use of multisoftware with the validation of shake table testing provides confidence for a safe design of such a complex structure.

European Vertical Reference System Influence in Latvia

Till 1 December, 2014, in Latvia the heights were determined in Baltic Normal Height System 1977. The national height system is determined by the Cabinet of Ministers and internal laws. Now for the change of the national height system to reconcile it with the European Vertical Reference System, amendments to the laws and regulations have been developed, but so far only the amendment to the Geospatial Information Law is in force, the amendment to the regulation of the Cabinet of Ministers is still not approved. This amendment declares the Latvia Height System based on the European Vertical Reference System in Latvia as the national height system.For height transformation, there is a transformation formula for each European country. After calculations it is seen that height difference between Baltic Normal Height System 1977 and European Vertical Reference System depends on point location in the territory (coordinates). This unequal height difference between both height systems will cause unequal height values on border connection points between Baltic countries. The aim of the research is to evaluate the European Vertical Reference System in Latvia. To reach the aim the following tasks are set: 1) to evaluate the components of transformation formulas; 2) using the transformation formulas to calculate height differences between Baltic Normal Height System 1977 and the European Vertical Reference System realization EVRF2007 for the territory of Latvia and also between Baltic Normal Height System 1977 and the Latvia Normal Height System; 3) to get height differences in the European Vertical Reference System on the borderlines of Latvia - Estonia and Latvia - Lithuania.

Reciprocal sign epistasis and truncation selection: When is recombination favorable in a pre-breeding program with a selfing species?

Since the dawn of agriculture, humans have applied artificial selection on traits of interest, regardless of their genetic architecture. Yet, still today, most models used to study and streamline this process overlook genetic interactions. In this study, we determined the conditions in which a target genotype can be fixed when truncation selection is applied on an epistatic trait. Previous studies have shown that reciprocal sign epistasis with two fitness peaks of unequal height involves multiple equilibrium states, i.e. below one critical parameter value, such as a critical recombination rate, one genotype may be fixed, and above it, another one may be fixed. Using a haploid bi-locus model, we identified which genotype would be fixed, and how quickly, in an infinite population selected for a phenotypic trait subject to reciprocal sign epistasis with unequal peak heights, depending on two criteria: the recombination rate and percentage of selected individuals. The critical parameter values at which bistability sets in, were also calculated. These results were complemented by stochastic simulations in finite populations. Our results confirmed that, in the case of fitness under reciprocal sign epistasis, high recombination rates induce blockage at the local optimum or attainment of an equilibrium state between the two peaks. However, if linkage disequilibrium is negative in the initial population, recombination is necessary to create the most favorable genotype. Therefore, in this case, reciprocal sign epistasis favors non-null recombination rates, particularly if selection is intense.

Expected seismic performance of irregular medium-span simply supported bridges on soft and hard soils

This paper presents the parametric study of irregular RC bridge structures subjected to strong seismic records. We determine the expected damages and the concentration demands on short piers of bridges with columns of unequal height located on soft and rigid soil sites. Medium length span bridges are analyzed using the most common structural configurations built in many countries with several height pier configurations. The structures were subjected to strong seismic ground motions recorded on soft and hard soils of earthquakes generated at subduction seismic sources. The parameters of interest in the study are the strength and stiffness characteristics of the substructure and the influence of the dynamic characteristics of the seismic records. The parameter combinations produced more than three hundred 3D non-linear time history analyses conducted with the Perform-3D software. Based on the evaluation of damages indexes, we determine the pier expected damages and the importance of the soil type, on the behavior of irregular pier bridge substructures. It is also quantified the impact of the pier configuration in the global behavior of the bridges and the influence of the shortest pier in the expected damages of the other piers. In most of the cases, the piers adjacent to the tallest piers of the bridge were the elements more affected by the irregularity.