Analytical modeling of composite steel-concrete frame systems

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.Equivalent macromodel based analytical tools, comprised of flexibility-based element models, are used to accurately represent the non-linear moment-curvature (force-deformation) response characteristics in structural systems using colunms of reinforced concrete or composite steel shapes encased in reinforced concrete (SRC), structural steel beams, and composite beam-column joints. To facilitate the modeling of inelastic deformations in joint regions, a panel element capable of representing joint shear distortions and joint bearing deformations was incorporated into an existing computer program, IDARC (Kunnath and Reinhorn 1994). The inelastic shear deformation characteristics of the joint panel were partly established from guidelines published by an ASCE Task Committee (ASCE 1993). Various hysteretic control parameters for members of the subassemblage, such as strength degradation, stiffness deterioration, and pinching (slip), were quantified based on observed experimental response (Kanno 1993). Potential failure modes of the frame subassemblage in the steel beam, reinforced concrete or SRC column, and composite joint were able to be represented in the proposed formulation. Experimental subassemblage testing performed at Cornell University (Kanno 1993) was used to validate the analytical platform. It is shown that the revised IDARC program can be used for seismic evaluation of composite structures and in the development of design guidelines to ensure desirable mechanisms in composite frame structures

GIS aided vulnerability assessment for roads

Road networks are vulnerable to natural disasters such as floods, earthquakes and forest fires which can adversely affect the travel on the network. However, not all road links equally affect the travel conditions in a given network; typically some links are more critical to the network functioning than the others. The first stage of study involves the investigation of geological conditions. Image classification used for extracting information classes from ‘Geological Map of Istanbul area’ image file. The resulting raster layer used to create thematic map. A reclassification was performed for lithologic types. The second stage involves analyzing topological situation. A slope map prepared and classified according to percentage of slope values. The third phase is the analysis and interpretation of the accumulated data to establish suitable and applicable road vulnerability scores. The information in the source data for each vulnerability factor are classified into three different vulnerability scores: +2 (considerably increases vulnerability), +1 (increases vulnerability) and 0 (does not increase vulnerability) by using a vulnerability score table. The study area was categorized into three different traffic analysis zones as: (1) least favorable area; (2) favorable area; (3) most favorable area. Vulnerability values obtained to measure serviceability of critical links in dense urban road networks and applies them to the case of ‘Beyoğlu’ region. Thematic layers were prepared using the Geographic Information System (GIS), and they were then combined to produce the serviceability of road links in the ‘Beyoğlu’ region. Consequently, A site specific vulnerability index is proposed, considering the serviceability of road links. A conceptual flowchart of the GIS processing steps taken to obtain the vulnerability index is illustrated

Development of a 30,000 kg heavy goods vehicle for LS-DYNA applications

In this paper, a finite element model of a 30,000 kg Heavy Goods Vehicle (HGV) was developed and validated against full-scale crash test data. Since this vehicle is a standard test vehicle in the European crash test standards, EN1317, development of an accurate vehicle model was deemed to be a positive contribution to the evaluation of roadside safety hardware. The vehicle model reproduces a FIAT-IVECO F 180 truck, a vehicle with four axles and a mass of 30,000 kg when fully loaded. The model consisted of 12,337 elements and 11,470 nodes and was built for and is ready to use with LS-DYNA finite element code from Livermore Software Technology Corporation. Data available from two previously performed full-scale crash tests, one on a steel bridge rail and the other on a portable concrete barrier, were used to validate the accuracy of the HGV model. Results of the finite element simulation study show that the developed HGV model shows promise and can accurately replicate the behaviour of an actual HGV in a full-scale crash test. Improvements such as the steering mechanism in the front axles and the suspension system are currently underway to make model more realistic

Humerus proksimal uç iki parçalı kırıklarının tek yönlü ve çok yönlü Kirschner teli ile tespitinin biyomekanik olarak karşılaştırılması

Objectives: The stability and effectiveness of uni-planar Kirschner wire (K-wires) was compared to multi-planar K-wires osteosynthesis combined with tension band wiring for fixation of two-part osteoporotic surgical neck fracture of the proximal humerus. Materials and methods: Two groups each with eight cadaveric elderly (mean age 72.6; range 70 to 80 year) frozen human humeri were used in the study. Transverse osteotomy of the proximal humerus was performed using a thin oscillating saw. The first group (group A) was fixed using two anterograde smooth K-wires, sent from lateral cortex, combined with tension band wiring. The second group (group B) was fixed using multi-planar (anterograde and retrograde) four smooth K-wires combined with tension band wiring on the lateral cortex. Biomechanical tensile properties for 3 mm displacement (gap load) and maximum load were assessed. Results: The mean value for the gap load was 1045.0±45.4 N (Newton) for group A and 1238.1±115.8 N for group B. Gap load values of groups were similar (p=0.01). The maximum load was 1261.8±52.4 N in group A and 1471.1±107.3 N in group B. The maximum load values were statistically higher in the multiplanar fixation technique (group B) when compared to that of the uniplanar fixation technique (group A), (p=0.004). Conclusion: Fixation in osteoporotic two-part surgical neck fractures of the proximal humerus using multiplanar K-wires combined with tension band wire provides substantially more effective stability compared to that of uniplanar fixation.Amaç: Humerus proksimal uç cerrahi boyun iki parçalı kırıklarında tek yönlü Kirschner teli (K-teli) ile tespit yönteminin stabilite ve etkinliği, çok yönlü K-teli ve gergi bandı yöntemi ile biyomekanik olarak karşılaştırıldı.Gereç ve yöntemler: Çalışma iki grup halinde düzenlendi. Her bir grupta sekizer adet dondurulmuş insan (ort. yaş 72.6; dağılım 70-80 yıl) kadavra humerus kemiği kullanıldı. Humerus proksimalinde ince el testeresi yardımı ile transvers osteotomi yapıldı. Birinci grupta (grup A) gergi bandı yöntemi ile güçlendirilen ve lateral korteksten antegrad olarak gönderilen iki adet düz K-teli ile tek yönlü tespit uygulandı. İkinci grupta ise lateral kortekste gergi bandı yöntemi ile güçlendirilmiş dört adet K-teli ile çok yönlü (antegrad ve retrograd) tespit uygulandı. Üç milimetre aralık oluşma sırasındaki yüklenme (ayrışma gücü) ve maksimum yüklenme miktarları biyomekanik olarak değerlendirildi. Bulgular: Ortalama ayrışma gücü, grup A’da 1045.0±45.4 N (Newton) ve grup B’de 1238.1±115.8 N olarak tespit edildi. Ayrışma gücü açısından, iki grup benzerdi (p=0.01). Maksimum yüklenme miktarı grup A’da 1261.8±52.4 N, grup B’de ise 1471.1±107.3 N olarak bulundu. Maksimum yükleme değerleri, çok yönlü tespit tekniğinde (grup B), tek yönlü tespit tekniğinden (grup A) istatiksel olarak yüksek bulundu (p=0.004). Sonuç: Humerus proksimal uç iki parçalı cerrahi boyun kırıklarının sabitlenmesinde, gergi bandı ve K-telleri ile güçlendirilmiş çok yönlü tespit yöntemi, tek yönlü tespit yöntemine göre daha etkilidir

Humerus distal kırıklarında çift plak osteosentezi, çift gergi bandı tekniğinden daha iyi biyomekanik stabilizasyon sağlar

Objectives: In this study we evaluated the stability and effectiveness of the double tension band osteosynthesis technique compared to the double plate osteosynthesis technique used for fixation of distal humerus fractures. Materials and methods: The study was performed on two groups, and in each group eight cadaveric, elderly (mean age 70-80) human humeri was used. An osteotomy was performed in the supracondylar region using a manual saw. The first group (group 1) was fixed with double 3.5 mm reconstruction plates, while the second group (group 2) was fixed with the double tension band technique, using crossing Kirschner wires. The osteotomy was designed so that the distal fragment would allow only a single screw per plate. The constructs were evaluated using a material testing machine. A linear non-cyclic load was applied until the failure of the constructs. The force which produced a 3 mm gap (3 mm gap strength), as detected visually with the aid of operating loupes, and the maximum load prior to failure of the fixation (maximum force) were measured from all tests. Results: The mean value for the 3 mm gap strength was 1356.29&plusmn;226.97 N for group 1 and 882.63&plusmn;305.21 N for group 2. The mean value of the maximum load strength was 1487.13&plusmn;298 N for group 1 and 1232&plusmn;107.62 N for group 2. There were significant differences in 3 mm gap strengths of the two groups (p=0.005). There was also a significant difference in the maximum load between the two groups (p=0.016). Conclusion: Double plate osteosynthesis technique is superior to double tension band osteosynthesis for the fixation of distal humerus fractures.Bu çalışmada Doğu Karadeniz bölgesi hamsilerinin avlama mevsimi süresince besin bileşenleri ve yağ asitleri komposizyonundaki aylık değişim incelenmesi amaçlanmıştır. Hamsilerin nem oranı ekim ayında en düşük (%64,93) iken nisan ayında ise en yüksek seviyeyede (%74,32) olduğu hesaplanmıştır (P<0,05). Buna bağlı olarak tüm aylardaki yağ seviyeleri ve aralık ve nisan aylarındaki kül miktarlarındaki değişim istatistiksel açıdan önemli bulunmuştur. İlaveten, avlanma mevsimi süresince doymuş yağ asitlerinden (SFA) C16:0, C14:0 ve C18:0, tekli doymamış yağ asitlerinden (MUFA) C18:1n9 ve çoklu doymamış yağ asitlerinden (PUFA) C22:6n-3 (DHA, dekosahekzanoik asit) ve C20:5n-3 (EPA, eikosapentanoik asit) en yüksek oranlarda bulunmuşlardır. Avlama mevsimi boyunca, ortalama omega–3 ve omega–6 değerleri sırası ile %30,33 ve %4,43 olarak hesaplanmıştır. EPA seviyesinde tedrici olarak bir azalma meydana gelirken, DHA seviyesinde ise ekim ayından nisan ayına kadar bir artış gözlenmiştir. Yağ asitlerinde av mevsimi boyunca yağ assitlerinde özellikle de DHA oranında belirgin bir şekilde bir değişimin olduğu gözlemlenmiştir

Traffic Safety at Median Ditches: Steel vs. Concrete Barrier Performance Comparison Using Computer Simulation

In Turkey, concrete V-shaped ditches are formed at the median section of divided highways to provide drainage. Recent accidents show that these ditches actually present safety risks to vehicles entering the medians. Vehicles either cross over the ditch, roll over, or become trapped in the ditch, depending upon the mass, size, speed, and angle of the entering vehicle. To overcome this safety risk and reduce the severity of these accidents, longitudinal barriers are installed along these ditches. Currently, in Turkey, steel barriers are extensively used to improve traffic safety at median ditches. In this paper, the crash performances of steel and concrete barriers used at medians with ditches are compared. A model of a standard steel EDSP-1.33 barrier and a model of a newly developed concrete C470 barrier were constructed, and impact simulations were performed for when they are installed at a ditch slope break point. A nonlinear finite element program, LS-DYNA, was used for the analysis. A 13,000 kg bus model was used to impact both barriers in accordance with European standard requirements for crash tests. Simulation results show that when the steel EDSP-1.33 barrier is used, the bus has the potential for excessive penetration of the ditch, with significant barrier deformation. Moreover, the barrier damage is extensive, resulting in increased maintenance costs. On the other hand, the concrete C470 barrier successfully contains and redirects the 13,000 kg bus impact, with minimal barrier deformation and safety risk. Even though the concrete barrier slides toward the inside of the ditch, the bus does not enter the ditch area and exits the barrier in a stable manner. Therefore, to increase traffic safety at ditches located at the median section of divided highways in Turkey, utilization of the newly developed concrete barrier C470 is recommended

Impact Performance Evaluation of a Crash Cushion Design Using Finite Element Simulation and Full-Scale Crash Testing

Crash cushions are designed to gradually absorb the kinetic energy of an impacting vehicle and bring it to a controlled stop within an acceptable distance while maintaining a limited amount of deceleration on the occupants. These cushions are used to protect errant vehicles from hitting rigid objects, such as poles and barriers located at exit locations on roads. Impact performance evaluation of crash cushions are attained according to an EN 1317-3 standard based on various speed limits and impact angles. Crash cushions can be designed to absorb the energy of an impacting vehicle by using different material deformation mechanisms, such as metal plasticity supported by airbag folding or damping. In this study, a new crash cushion system, called the ulukur crash cushion (UCC), is developed by using linear, low-density polyethylene (LLDPE) containers supported by embedded plastic energy-absorbing tubes as dampers. Steel cables are used to provide anchorage to the design. The crashworthiness of the system was evaluated both numerically and experimentally. The finite element model of the design was developed and solved using LS-DYNA (971, LSTC, Livermore, CA, USA), in which the impact performance was evaluated considering the EN 1317 standard. Following the simulations, full-scale crash tests were performed to determine the performance of the design in containing and redirecting the impacting vehicle. Both the simulations and crash tests showed acceptable agreement. Further crash tests are planned to fully evaluate the crashworthiness of the new crash cushion system

Soil based design of highway guardrail post depths using pendulum impact tests

Guardrails are passive road restraint systems (RRS) used at roadsides and medians to improve road safety. In the case of inadequate post embedment depth of soil driven posts may not function as intended and design cannot provide adequate safety nor security for the impacting vehicles. In general, the height of the steel guardrails varies between 1600 and 2400mm. However, the characteristics of the soil where the guardrails are driven are not taken into consideration. In other words, a constant depth of guardrail is used regardless of the type of soil. Post embedment depths (PED) in steel guardrail systems are currently determined based on strong soil properties. The crash performance of these designs may not be appropriate for locations where soil conditions are weaker than tested conditions. In this study, a series of field impact tests were performed on soil embedded posts to determine optimum PED for three different soil conditions, namely hard, medium hard and soft soil. A pendulum device is used to perform dynamic impact tests on C type (C120x60x4), H type (H150x90x6) and S type (S100x50x4.2) posts. Seven different PED values were used for each type of soil. A total of 63 impact tests proved that increased soil stiffness resulted reduction in PED for the posts. Optimum PED values are determined based on energy absorption of posts. With the use of optimum length guardrail posts considerable amount of installation time, labor and material savings are expected