صين و الهند يعتمدون بدرجة كبيرة على الحديد المعاد تدويره كمادة أولية لانتاج الصفائح لهذا الجودة ليست مستقرة لأن المادة الاولية تختلف كل مرة. المعروف أن الحديد المعاد تدويره يحتوي نسب مختلفة من الشوائب مثل السيليسيوم و الكبريت و عند اعادة سبكه يصبح صعب تنقبته من الشوائب لأن هذه العملية تتم في الأفران العالية عند تذويب خام الحديد.
مصدر لو أمكن بما انك تتحدث بصيغة التعميم فبالطبع عليك إثبات ذلك بشكل شامل وأكرر لو أمكنك ! ... لكن لو الامر رائ من حضرتك فلا داعي لاي مصدر بالطبع .
هل يمكن مصدر على هذا الكلام لأن الامريكان يستخدمون الكود AISC للبناءات المعدنية و الذي يشترط استعمال steel shapes حسب كود astm و هذا الكود لا تستطيع المصانع الصينية تلبية شروطه لأنه ليس لديها رخصته ما عدا ألواح الصفيح
الأقسام الرئيسية من البرج والكابل والسطح من جسر خليج سان فرانسيسكو - أوكلاند الجديد المعلق مصنوع بالصين مع العلم كان هناك أكثر من 200 شخص أرسلتهم ولاية كاليفورنيا والمقاول الرئيسي عن المشروع بدوام كامل لمصانع الصين لمراقبة جميع جوانب عمليات التصنيع وأجروا إختبارات لتحقق من جودة الصلب الصيني ، بمدينة نيويورك شاركت الشركات الصينية في محطة قطار ومترو وجسر كما تعرف ، شركتين صينيتين شاركوا بتقديم الصلب والخدمات بمشروع جسر تانانا للجيش الأمريكي بالأسكا وقد تم إحضار العوارض من الصين تحت مراقبة مشرفيين من الولايات المتحدة بدوام كامل أثناء التصنيع لضمان الجودة مع زيارات لمسؤولين من مجموعة Kiewit وهي من أكبر المجموعات للبناء والهندسة بأمريكا الشمالية .
This assembly will be performed early next year by American labor. But the massive cable, key sections of the iconic tower and deck were all made in China, which is emerging as an infrastructure powerhouse in more places than San Francisco. For example, Chinese companies have contracted with New York City for a bridge, the subway system and a commuter train platform.
The steel contract went to a state-owned Chinese company, Shanghai Zhenhua Heavy Industries, which had several advantages: modern production facilities, ships to deliver the steel and, of course, low-cost labor. A Chinese steel polisher makes about $12 a day.
It wasn't just the cost of labor that made Chinese steel more attractive, Anziano says. He says American steel fabricators don't have the capacity for a job like the Bay Bridge. When union and industry groups questioned the quality of the Chinese steel, Anziano says, the state and the contractor sent more than 200 people to China to watch over the fabrication process.
"In this particular case, we had full-time staff on site over in China — 24/7 — that monitored all aspects of fabrication work and performed their own quality-assurance testing," he says. "So we have a very high level of assurance about what we are getting."
https://www.npr.org/2011/09/16/140515737/california-turns-to-china-for-new-bay-bridge
The Verrazano-Narrows Bridge was a feat of American engineering when it was built across New York's harbor in the 1960s. Now, it's being repaired with steel made in China.
Chinese steel imports have surged so far this year, even as U.S. producers are awash with excess domestic capacity. Chinese steel was also recently used in the San Francisco-Oakland Bay Bridge.
The reason is partly because Chinese-made steel is cheaper. In fact, U.S. steel companies argue its price is unfairly subsidized, and want the U.S. government to restrict imports as much as possible. China claims it is simply a more efficient producer.
Last year, New York's Metropolitan Transportation Authority awarded a $235.7 million contract to a California contractor to repair the Verrazano-Narrows, a towering suspension bridge that is still the longest in the U.S.
The contractor, Tutor Perini Corp. , subcontracted the fabrication of steel decks for the bridge to China Railway Shanhaiguan Bridge Group, which the MTA says is using 15,000 tons of steel plate made by China's Anshan Iron & Steel Group. The decks will replace the two-level bridge's concrete upper roadway.
https://www.wsj.com/articles/SB10001424127887324049504578545431938331880
This Bridge project is a 3,300 ft. long railroad bridge, 7,344 tons, that is part of the Northern Rail Extension connecting the North Pole with Delta Junction, Alaska. Fabrication of this bridge was by CRSBG, China.
Atema provided technical fabrication consultant services which included: US code interpretation and compliance; change orders; RFI’s; inspection and testing; and cost savings ideas to ensure the project was on time, within budget, and met or exceeded contract requirements.
https://www.atema.com/project/tanana-river-bridge/
The word
Tanana means “trail river.” The new Tanana River Bridge in Salcha, Alaska, a small community located south of Eielson Air Force Base, provides a trail across the river—a vital connection to 1 million acres of U.S. military training facilities in Alaska. Construction of the bridge marks the completion of the first phase of the Alaska Railroad Corp.’s (ARRC) Northern Rail Extension, a project that will create an 80-mile rail network between North Pole and Delta Junction, Alaska. The extension provides a safer, all-weather transportation option and gives the military improved, year-round access to training facilities south of the river that previously were accessible only by ice roads during winter.
One of the major challenges of this project involved transporting by truck 80 165-ft-long girders 330 miles on the Richardson Highway from the port of Valdez, Alaska, to Salcha, Alaska. The girders were fabricated in China and shipped to Alaska.
Another logistical challenge involved girder fabrication in China. This approach resulted in additional quality-assurance and quality-control activities to confirm that delivered materials met the contract documents. Third-party inspectors observed fabrication full time on-site, and these efforts were supplemented by occasional site visits by representatives from the ARRC and Kiewit.
https://www.roadsbridges.com/taming-beast
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