Relating Field Energy Attenuation in Portland Cement Concrete Pavements to Fracture Mechanics

Asset management of infrastructure is fundamental for maintenance planning and preservation of common property. A robust testing program is needed to assess the present-day status and for proper actions in time to minimize the ongoing depreciation of value. As a matter of fact, Portland Cement Concrete pavements show very little deterioration even after many years in service. Thus, it may be difficult to accurately predict the present asset value, other than using linear relations to the presumed design life. The primary reason for failure is cracking in concrete pavements, so assessing the dissipated energy from the load-deformation relation from a given load could be utilized for the purpose. The dissipated energy, i.e. the work data can be assessed by a falling weight deflectometer test, mimicking the passing of a truck or aircraft wheel load. In the present study, dynamic field data are evaluated, and the input data needed for the fracture mechanics model are used to predict the pavement life regarding cracking. To predict fracture energy and assess rolling resistance as well in concrete pavements, we need to consider the energy balance of the pavement system. To assess dissipated energy, falling weight deflectometer time histories are used to evaluate the pavement contribution to rolling resistance. Such analyses include all layers in the structure including the subgrade, so in the present case a way of sorting the dissipation at various depths is investigated. Field data were collected from a site, at mid-life of the predicted design life. The failure was confirmed several years later, and the remaining life was compared with the assumption that the dissipated energy near the edge was enough to initiate the cracks within the actual time to failure. Conversely, the dissipation at the mid-slab position was below the limit. The data from the field test were also used as an input for a finite element model to see if it was viable to further improve the prediction. The method seems to be promising, but more data are needed as the present set only represents the mid-life status.

The Effects of Deteriorated Boundary Conditions on Horizontally Framed Miter Gates

The U.S. navigable infrastructure is a system of waterways dependent upon hydraulic steel structures (HSS) to facilitate the passage of ships and cargo. The system is linear in the sense that if one HSS is impassable, the entire river system is halted at that point. The majority of the HSS in this system were built in the first half of the 20th Century, and over seventy percent of them are past or near past their design life. Miter gates are critical HSS components within the system and many are showing signs of structural distress from continued operation past their design life. Common distress features include shear cracking within the pintle socket, partially missing Quoin blocks, fatigue fracturing, and bolt failure in the pintle region. This article focuses on gaining a fundamental understanding of the consequences of quoin block deterioration on a miter gate. The work was conducted by developing a computational model of a miter gate with different levels of quoin block deterioration. This model was validated using analytical solutions. The deterioration results demonstrated that the miter gate thrust diaphragm and quoin post experienced changes in their limit states due to deterioration. The results also demonstrated that the miter gate could overcome up to 10% of quoin block deterioration.

New Recommendations for Offshore Wellhead Platform Structural Design Due to Well Conductor Casings Failures: Outcome of a Study Based on Actual Findings

Detailed study on structurally failed well conductors on offshore wellhead platforms lead us to believe that existing assumptions of conductors transfer only lateral loadings to wellhead platforms while entire well vertical loading will be carried by conductor itself; could be wrong. The well conductors could become ‘forced’ to carry a very large vertical loads incase the conductors are structurally failed; especially once exceeded its original design life. As such, some new considerations during the wellhead platform design, which need to be followed, are recommended here. These are to cater any catastrophic eventuality of conductor failures which will restrain further collapse of the conductors or to avoid any progressive collapse of the platform. The recommendations are from a study based on actual findings observed recently in the offshore field. The connection between conductors and platforms are conventionally designed as guided based on the load transfer assumptions. That is the huge vertical loadings from internal conductor casings and associated items were not a concern for platform design structural engineers, traditionally, and as such the conductors were designed to be structurally connected to the wellhead platforms using vertical guides. Due to extended design service life of platforms, in many cases the design life went up to two times of their original design life, severe degradation of structural integrity of the conductors were observed in the field. Structural analysis and assessment were carried out on many old intact and failed conductors, in the offshore field, in order to assess its structural and loading behavior with respect to supporting wellhead platforms. The study provided that the failed conductors were leaning / collapsing to the wellhead platform resulting in transferring a huge vertical loads which originally were designed to be carried by conductors alone. This huge transfer of vertical loads from conductor to the platform was unexpected and was not considered in platforms original design. Therefore, the platform should have sufficient structural strength to cater such extreme eventuality to avoid the risk of complete collapse. A risk assessment of a tilted / failed conductors indicated that the consequence of total failure of a conductor could be catastrophic in case the platform failed to resist the collapsing conductors. This paper presents the details of the study carried out on aged wellhead platforms, having failed long serving conductors, in Giant offshore field, Abu Dhabi, along with details of new recommendations to be followed while designing new wellhead platforms. The paper also recommends the structural design consideration to be followed while designing wellhead platforms in-case a conductor repair is necessitated in future.

EVALUASI KERUSAKAN PERKERASAN LENTUR RUAS TOL JAKARTA-CIKAMPEK DAN ALTERNATIF PENANGANANNYA

The most common causes of road damage are the design life of the road that has been passed, waterlogging on the road due to poor drainage, or even traffic load which can cause the service life of the road to be shorter than planned. To find out the conditions on the Jakarta-Cikampek Toll Road. Calculates the value of road pavement conditions calculated using the Indeks Kondisi Perkerasan (IKP) on the Jakarta-Cikampek Toll Road. To find out what kind of treatment we should do for the damage that occurs. The Indeks Kondisi Perkerasan is a quantitative indicator of pavement conditions that has a range of values ranging from 0 – 100, with a value of 0 representing the worst pavement condition while 100 representing the best pavement condition. The IKP method has a level of handling type for each IKP value. According to the IKP guidelines, the type of handling that must be carried out with an average IKP value of 96,32 is routine maintenance. For further research, it’s necessary to conduct a direct survey, so that accurate results can be obtained. It is necessary to study with various methods to be able to compare the level of accuracy of a method. ABSTRAKPenyebab kerusakan jalan yang paling umum adalah umur rencana jalan yang telah dilewati, genangan air pada jalan yang diakibatkan drainase yang buruk, atau bahkan beban lalu lintas yang berlebihan yang dapat menyebabkan umur pakai jalan akan menjadi lebih pendek daripada perencanaannya. Untuk mengetahui kondisi pada jalan Tol Jakarta-Cikampek. Menghitung nilai kondisi perkerasan jalan jika dihitung dengan Indeks Kondisi Perkerasan (IKP) pada ruas Tol Jakarta-Cikampek. Untuk mengetahui penanganan seperti apa yang harus kita lakukan terhadap kerusakan yang terjadi. Kondisi Perkerasan atau IKP adalah indikator kuantitatif (numerik) kondisi perkerasan yang mempunyai rentang nilai mulai 0 – 100, dengan nilai 0 nya menyatakan kondisi perkerasan paling jelek sementara 100 menyatakan kondisi perkerasan terbaik. Metode IKP memiliki tingkat jenis penanganan tiap nilai IKP. Menurut pedoman IKP, jenis penanganan yang harus dilakukan dengan nilai IKP rata-rata 96,32 adalah pemeliharaan rutin. Untuk penelitian selanjutnya, perlu untuk survei secara langsung, supaya hasil yang didapat lebih maksimal. Perlu diteliti dengan metode yang beragam untuk dapat membandingkan tingkat keakuratan sebuah metode.

Exploration on the Materials Quality Control of Railway Vehicle Weld Structure Based on Service Safety Demand

With the continuous increasing of service-rail-vehicle in China, some defects such as cracks appeared at different stages of service when they had not reached the design life, while current theories and methods cannot explain the appearance of defects, which brought risks and hidden dangers to the operation of the vehicles. It was found that the reasons were mainly caused by one or several factors such as material performances, design, manufacturing process and operating environment. Since more and more sensors being installed on the vehicles to supervise the health of structure, it is more improtant to focus on the performances of materials. Through comparing different material standards including international, national, railway industry and enterprise standards, as well as the technical delivery conditions of other industries, it was recommended that the fracture mechanical parameters such as fracture toughness and fatigue crack growth should be proposed into the materials quality control regulations of original equipment manufacturers (OEMs). Furthermore, based on the testing data of materials from OEMs, several suggestions were proposed on the basic performance of materials such as raising the requirements contained impact, metallography and corrosion resistance properties in order to provide guarantee for the service safety of vehicles.

Testing of Intermediate Layer Laston Mixture Characteristics Using Sungai Pucak Stone, Maros Regency

The implementation of road pavement construction so far has used materials imported from other places, and most of the road pavement constructions have been damaged before reaching the design life, so maintenance is carried out and even additional coating is given. This study aims to test the characteristics of the mixture of Laston Lapis Antara by utilizing Sungai Pucak aggregate according to laboratory tests. The research method is the Conventional Marshall test which is used to determine the KAO, then the manufacture of the KAO test object to obtain the Marshall Remaining Stability (SMS). The results showed that the characteristics of the aggregates originating from the Pucak River, Maros Regency for the Laston Lapis Antara mixture were in accordance with the General Specifications of Highways in 2018. The results of the characteristic test of the conventional Marshall mixture obtained that the values of stability, flow, VIM, VMA, and VFB all met the General Bina specifications. Marga in 2018. The Marshall Immersion test has complied with the 2018 General Highways specifications, where the value is 95.56%≥90%.

Time-Dependent Damage Estimation of a High-Rise Steel Building Equipped with Buckling-Restrained Brace under a Series of Earthquakes and Winds

This study investigates the cumulative damage of a 20-story high-rise steel building equipped with buckling-restrained braces (BRB) under the likely occurrence of earthquake and wind events in the design life of the building. The objective of this research is to introduce a method for evaluating the cumulative damage of BRBs under multi-hazard events that are expected to occur during the service life of a high-rise building in order to achieve a safer building. A methodology is proposed using a Poisson point process to estimate the timeline of earthquake and wind events, wherein the events are assumed to be independent in nature. The 20-story high-rise steel building with BRBs is designed according to the Japanese standard and analyzed using the finite element approach, considering nonlinearities in the structural elements and BRBs. The building is analyzed consecutively using the timeline of earthquakes and winds, and the results are compared with those under individual earthquakes and winds. In addition to the responses of the frame such as the floor displacement and acceleration, the damage of BRBs in terms of the damage index, the energy absorption, the plastic strain energy, and the maximum and cumulative ductility factor are evaluated. It is observed that the BRB’s fatigue life under multi-hazard scenarios is a multi-criteria issue that requires more precise investigation. Moreover, the overall building’s performance and BRB’s cumulative damage induced by the sequence of events in the design life of the building is significantly larger than that under an individual event.

Social narcissism – how society pushes us to overestimate our capacities, leaving many behind

The following introduces the concept of overlife, not claiming that it is an entirely new idea, however suggesting that it is a suitable term to bring different problems of contemporary societal development together. Broadly speaking, overload is defined as simultaneously condensing patterns of life and the actual living, i.e. intensifying living by establishing patterns of multitasking; however, doing so occurs for the price of a shallowed concept of life by a differentiated system of standardization. Simplification of cognition and education, not least in the context of digitization, are important factors: The apparently increasing control, everybody experiences, goes hand-in-hand with increasing difficulties of understanding – and enjoying – the complexity with which we are confronted. Still, although this seems to be a secular process concerning humanity and humans in general, control and power remains in the hands of a few who, as individuals and corporations, design life and society. Paradoxically, the theoretically gained possibility to answer complex questions and develop long-term perspectives, turns, at least under capitalist conditions, into narcissistic idiosyncrasies, and wasting huge amounts of monies for the thrill of egos instead of strategically developing socio-economic strategies addressing major challenges as poverty, environmental threats, digitisation and new forms of stupidification