Simulation of Palu IV Bridge Collapse using Near-Fault Ground Motions

<p>The earthquake near Palu, Sulawesi (Indonesia) on September 28, 2018 with a magnitude of M7.4 was caused by a shallow strike-slip of Palu-Koro fault. The earthquake and the subsequent tsunami have caused the collapse of the Ponulele Bridge (Palu IV Bridge). The steel box bowstring arch bridge was located near-fault regions (within 1,5 km from fault line) that have not been identified during the design process. This bridge may have been damaged by the presence of fling-step pulses in the near-fault pulse-type ground motions that increases the damaging potential of such ground motions. This paper presents the failure simulation of the bridge subjected to the near fault pulse type time history with spatial variation ground motions applied on multiple bridge supports. From the simulation, it is concluded that the near fault effects and the spatial variation of the ground motion have increased significantly the seismic demand on the bridge. This increase causes the failure in the anchorage of the bridge bearing system.</p>

Effects of Fatigue Damage on Bond Behavior between Corroded Rebar and Concrete

Bond degradation due to rebar corrosion and fatigue loading may affect the serviceability and even safety of reinforced concrete (RC) bridges. 15 specimens confined with stirrups were cast for eccentric pull-out tests, and 12 of them were corroded with the target mass loss of 0.03 by the impressed current method. Monotonic pull-out tests were conducted on three corroded and three uncorroded specimens. Wavy descending branch was found in bond stress-slip test curves of uncorroded specimens attributed to stirrup confinement, however it disappeared in those curves of the corroded specimens due to the corrosion loss of rebar transverse ribs. Based on the tested monotonic bond strength, the other nine corroded specimens of different fatigue damages were obtained through repeated loading with different levels and cycles before undergoing monotonic pull-out tests. It is observed that the relative slip increases with a gradually decreasing rate as the loading cycles increase. The monotonic tests of specimens with fatigue damage show that the bond strength increases to a certain value and then decreases with the increase of fatigue loading cycles. Moreover, the higher the loading level is, the fewer cycles are needed to reach the maximum bond strength. In addition, the peak slip corresponding to bond strength decreases with the increase of fatigue loading cycles.

Globalization of Structural Design and Construction in Developing Countries

<p>Globalization is shrinking the world in many senses, but at the rates at which it is happening in various countries is different depending on where any country is situated on the scale of development; however, in construction industry, the level of globalization is much lower than in other segments of the economy, across most of the countries. True and the desired level of globalization can be achieved only when the design and construction practices are globally harmonized but adopting context-specific customization to accommodate the genius of each country. This paper aims to promote such diversity in unity. The global construction industry will be the biggest beneficiary of such a globalizing movement. World has faced several crises in different countries due to many reasons like war, terrorism, bad governance, which is leading to unemployment even among highly capable engineers. A globalized environment in construction would leverage global talent despite such adverse socio-political and environmental differences. Cost-optimization is likely to take on a different meaning, gaining a wider level of acceptability across the globe.</p>

The 200 Year Bridge - The New Goethals Bridge as a Roadmap

<p>The Port Authority of New York and New Jersey has completed the replacement of the congested and functionally obsolete Goethals Bridge, a circa 1928 steel cantilever truss bridge, with a dual-span modern cable-stayed bridge connecting Elizabeth, New Jersey and Staten Island, NY. Designed as a 150 year service life structure, the newly opened crossing paves the way towards achieving the possibility of a 200 year bridge, both in material durability, structural redundancy / resilience, and modal flexibility.</p><p>The new crossing features three eastbound and three westbound lanes plus a 3 m wide shared use path (SUP) for bicycles and pedestrians. To accommodate future expansion, the superstructure of the cable stayed spans is designed to receive steel framing to support a variety of possible transit options including light rail, while the substructure need not be strengthened for this future load. With a 274 m main span, the new crossing provides a significant maritime navigational improvement over the original 205 m steel truss span.</p><p>Herein we focus on the strategic application of corrosion protection strategies to achieve the long service life in a competitive bid environment, structural benefit of the design as relates to resiliency, modal flexibility, and operational redundancy to withstand extreme events.</p>

The Fatigue Performance of High Performance Concrete Composite Girder

<p>The application of high performance concrete has been increasingly concerned in the negative flexural region of steel‐concrete continuous composite girder because of its favorable tensile performance. However, the unclear cyclic and ultimate performance of a high performance concrete composite girder results to the problems which hinder the further application. In this case, a series of fatigue negative bending tests on HPC composite girders and fatigue push‐out tests on stud connectors in HPC were executed. The test results showed that the fatigue slip in the HPC composite girder was smaller than the normal concrete composite girder, and the fatigue life of stud in HPC was longer than the one in normal concrete. Meanwhile, according to the comparison between the stud fatigue live evaluations and test results, the AASHTO‐based evaluations were comparatively with larger safety redundancy, and JSCE was close to the test results but had smaller safety redundancy.</p>

Potential Insights from Performance-Based Design of Fire Protection in Tall Buildings

<p>Analysis of the structural performance under realistic fire scenarios makes Performance Based Fire Engineering (PBFE) particularly suited to design fire protection of tall buildings. In this paper, the impact of using the PBFE method is studied using a standard tall building as an example. The parametric temperature- time curves recommended in Eurocode 1 are used to define the fire loads. The thermal and mechanical response of the building to the imposed fire loading is subsequently analyzed by means of a finite element model of the mixed-use tower. Particular care is devoted to analyzing the performance of a steel truss at a transfer level, to study potential global effects of a local fire, effects that are not studied or understood within the prescriptive design framework.</p>

Load-carrying capacity of RC members in the viaducts of Railway where ASR occurred

<p>In Japan, measures against ASR have been started since the late 1980s, but it is no exaggeration to say that all buildings built before that may be affected by ASR. Deterioration and damage due to ASR are remarkable in the section from around TsubameSanjo Station on the Joetsu Shinkansen operating in East Japan Railway Company to around Niigata Station, and there are situations where maintenance management is difficult. Currently, if there are major defects in regular inspections, we will carry out surface treatment etc., but we are starting to study how to prevent the ingress of water at the stage of minor defects in order to prevent the progression of ASR. When waterproofing the surface of a structure in which a crack or the like is generated by ASR, the effects of water blocking effect and reduction of the amount of water in concrete are not well known. In this report, RC slab members exposed and stored for about 15 years (about 40 years after completion) were used as RC beam specimens, and were dried to some extent on the assumption that moisture was blocked, and a loading test was performed. As a result of the loading test, the maximum strength of the RC beam specimen was larger than the calculated shear strength. From this result, it is considered that the damage level of the current ASR does not have the effect of reducing the shear resistance so much.</p>

Design of Integral Abutment Bridges for a Lateral Slide Replacement

<p>Jacobs is completing the preliminary and detailed design of two bridge replacements on County Road 17 in Ontario, Canada using an accelerated bridge construction technique known as lateral slide (also known as slide-in-bridge or jack-and-slide) for the Ontario Ministry of Transportation. The Hawkesbury Creek &amp; CNR Overhead is a multi-span slab-on-girder structure spanning a creek and locomotive tracks. The Highway 34 Overpass is a single-span rigid frame structure spanning over the main road leading to the Town of Hawkesbury. The existing structures are approaching the end of their useful service life and rehabilitation is no longer a viable option. The new superstructures will be built on temporary supports located north of the existing structures. The new foundations consist of non-standard integral abutment details supported by composite caissons drilled through the existing roadway using temporary lane closures along County Road 17. This is an alternative to conventional integral abutment design which typically consists of a single row of steel H-piles. County Road 17 will be closed for up to four weeks to permit rapid demolition of the existing structures followed by the lateral slide. This is the first integral abutment lateral slide in the Province of Ontario. New design concepts, non-standard details and construction sequencing have been developed to achieve an economical, practical and robust design solution.</p>

Handling Accidents and Calamities in Hydraulic Structures

<p>Hydraulic closures in dams, navigation locks and flood barriers belong to the most heavily loaded structures built by people. While ensuring their sufficient strength is the main engineers’ concern, one must also be prepared to adequately handle their failures. Identifying and reducing the risks of failures is an issue of wider scope than structural analysis alone. Once an accident happens, proper investigations, handling the losses and planning the repair become primary goals. This paper gives a general guidance on these issues reflecting the European (mainly Dutch) and American practice. The discussion includes both handling the situations immediately after the accidents, and the choice between repair and replacement of a damaged structure. Accidents are infrequent events of very diverse causes and consequences, therefore this discussion has an engineering rather than statistical character.</p><p>Both authors contributed to resolving accidents and failures of hydraulic structures, in the roles varying from investigation or design leader to repair manager. They were also consulted or made part of crisis teams in a number of other so-called “upset events”. This paper combines the highlights of their own experience and the practices being followed by the waterway administrations in the USA and the Netherlands. The selected examples are also from these countries, but can be seen as reflecting issues and concerns anywhere.</p>

Timber-concrete composite frame joint for high-rise buildings

<p>Timber is one of the few renewable materials that improves its structural properties when combined with concrete. The composite of timber and concrete increase stiffness and fire protection, unlike timber when used alone. In contrast to concrete structures, timber-concrete composite (TCC) structures reduce the carbon footprint and the specific weight of a building. At the Chair of Hybrid Structures - Structural Concrete of BTU Cottbus-Senftenberg a moment-resistant TCC joint was developed for multi-story frames, which can be used as a structural system for high-rise buildings. Facts like a modular construction, a fast assembly and a plug-in connection were aspects that shaped the development. A high rotational stiffness and load-bearing at the composite joint was also achieved using high strength beech laminated veneer lumber (LVL).</p><p>The TCC frame works on its own and in combination with other bracing systems. Initial investigations on the load-bearing behavior were carried out using numerical analysis followed by experiments on real-sized joints in further studies. First results will be presented in this paper. The developed TCC joint as part of structural systems offers a high variability and can thus contribute to tomorrow’s sustainable vertical growth of cities.</p>