title: Moment capacity of cold-formed channel beams with edge-stiffened web holes, un-stiffened web holes and plain webs

authors: Sivaji, Vivekanandan

subjects: Science & Technology

abstract: Cold-formed steel (CFS) channel beams are an increasingly popular choice as load-carrying members in building structures. Such channel beams often include web holes for installation of services. Traditional web holes are normally punched and are un-stiffened. This can restrict the size and spacing of web holes. Recently, a new generation of CFS channel beams with edge-stiffened web holes has been developed and used widely in New Zealand. However, no experimental investigation has been reported in the literature for such channel beams under bending. In this paper, a total of 215 results comprising 16 four-point bending tests and 199 finite element analysis (FEA) are reported on the moment capacity of CFS channel beams with both edge-stiffened and un-stiffened web holes. For comparison, channel beams without web holes were also tested. For all specimens, initial imperfections were measured using a laser scanner. A nonlinear elasto-plastic finite element (FE) model was also developed, and the results showed good agreement with the test results. A parametric study was conducted using the validated FE model to investigate the effects of beam length, hole diameter, stiffener length and fillet radius on the moment capacity of CFS channel beams. It is shown that for the case of a channel beam with five edge-stiffened web holes, the moment capacity increased by as much as 14.5%, compared to that of a plain channel beam. For comparison, the same section with un-stiffened web holes had a 13.6% reduction in moment capacity, compared to that of a plain channel beam. Furthermore, the accuracy of current design guidelines in accordance with the American Iron and Steel Institute (AISI) and Australia/New Zealand (AS/NZ) standards were verified by comparing the tests and FEA results against the design strengths for moment capacity of CFS channel beams without web holes. On the other hand, for CFS channel beams with web holes, the moment capacity obtained from tests and FEA were compared against the moment capacity calculated from the design equations of Moen and Schafer. Upon comparison, it was found that the AISI and AS/NZS can closely predict the moment capacity of CFS channel beams without web holes. The Moen and Schafer design equations were found to be over-conservative by around 11% and 28% for moment capacity of CFS channel beams with un-stiffened and edge-stiffened web holes, respectively.

text: Moment capacity of cold-formed channel beams with edge-stiffened web holes, un-stiffened web holes and plain webs Cold-formed steel (CFS) channel beams are an increasingly popular choice as load-carrying members in building structures. Such channel beams often include web holes for installation of services. Traditional web holes are normally punched and are un-stiffened. This can restrict the size and spacing of web holes. Recently, a new generation of CFS channel beams with edge-stiffened web holes has been developed and used widely in New Zealand. However, no experimental investigation has been reported in the literature for such channel beams under bending. In this paper, a total of 215 results comprising 16 four-point bending tests and 199 finite element analysis (FEA) are reported on the moment capacity of CFS channel beams with both edge-stiffened and un-stiffened web holes. For comparison, channel beams without web holes were also tested. For all specimens, initial imperfections were measured using a laser scanner. A nonlinear elasto-plastic finite element (FE) model was also developed, and the results showed good agreement with the test results. A parametric study was conducted using the validated FE model to investigate the effects of beam length, hole diameter, stiffener length and fillet radius on the moment capacity of CFS channel beams. It is shown that for the case of a channel beam with five edge-stiffened web holes, the moment capacity increased by as much as 14.5%, compared to that of a plain channel beam. For comparison, the same section with un-stiffened web holes had a 13.6% reduction in moment capacity, compared to that of a plain channel beam. Furthermore, the accuracy of current design guidelines in accordance with the American Iron and Steel Institute (AISI) and Australia/New Zealand (AS/NZ) standards were verified by comparing the tests and FEA results against the design strengths for moment capacity of CFS channel beams without web holes. On the other hand, for CFS channel beams with web holes, the moment capacity obtained from tests and FEA were compared against the moment capacity calculated from the design equations of Moen and Schafer. Upon comparison, it was found that the AISI and AS/NZS can closely predict the moment capacity of CFS channel beams without web holes. The Moen and Schafer design equations were found to be over-conservative by around 11% and 28% for moment capacity of CFS channel beams with un-stiffened and edge-stiffened web holes, respectively.

year: 2020-12-01

title: Rising regional inequality in China: Fact or artifact?

authors: Li, Chao

subjects: inequality

abstract: China’s local populations can be counted in two ways: people with hukou household registration from each place, and people actually residing in each place. For most of the first three decades of the reform era the hukou count denominated per capita GDP figures. Output and living standards were overstated in coastal provinces and understated in the interior. The distortion grew bigger as the non-hukou migrants increased to over 100 million. Much of the apparent increase in inter-provincial inequality is a statistical artifact caused by this distortion. The recent switch to using the resident count to denominate GDP introduced new distortions.

text: Rising regional inequality in China: Fact or artifact? China’s local populations can be counted in two ways: people with hukou household registration from each place, and people actually residing in each place. For most of the first three decades of the reform era the hukou count denominated per capita GDP figures. Output and living standards were overstated in coastal provinces and understated in the interior. The distortion grew bigger as the non-hukou migrants increased to over 100 million. Much of the apparent increase in inter-provincial inequality is a statistical artifact caused by this distortion. The recent switch to using the resident count to denominate GDP introduced new distortions.

year: 2013

title: John William Richard Guilding

authors: Hart, Philip

abstract: Born in Auckland in 1842, by his late teenage years John William Richard Guilding was trading with Maori in the Piako district. Protected by a rangatira, he established a store at Kerepehi, but despite being known to be ‘friendly’ with Maori he was driven off after the start of the Waikato War. In 1864, again with the approval of a rangatira, he erected a store on the site of the future township of Thames. Although he claimed to have found signs of gold there, he was not the prospector who produced the samples that led to the opening of the goldfield. In 1869 he was appointed a licensed interpreter, in which role he assisted both the Crown and private individuals to acquire Maori land. Some of these transactions created controversy, and he was accused of tricking Maori. In 1875 his attempt to use his position as James Mackay’s interpreter to acquire a lease of land at Tairua for his own financial gain provoked much criticism, and his ‘irregular practices’ led to his dismissal as a licensed interpreter in 1883. He would continue to act for individuals as both an interpreter and a land agent in Ohinemuri and Te Aroha in subsequent years.
Guilding’s close links with Maori were in part explained by his private life. Having married a ‘half-caste’ who later left him for another man, he had three more ‘marriages’ and several more children, who were brought up in Pakeha ways. Financially, he always struggled, filing as bankrupt twice and dying in straightened circumstances. At Te Aroha he held several minor official positions, sometimes being criticized for his performance. Active in local politics, he was generally unpopular and was never elected to the positions he sought. Throughout his life his reputation amongst a sizeable number of his contemporaries was poor.

text: John William Richard Guilding Born in Auckland in 1842, by his late teenage years John William Richard Guilding was trading with Maori in the Piako district. Protected by a rangatira, he established a store at Kerepehi, but despite being known to be ‘friendly’ with Maori he was driven off after the start of the Waikato War. In 1864, again with the approval of a rangatira, he erected a store on the site of the future township of Thames. Although he claimed to have found signs of gold there, he was not the prospector who produced the samples that led to the opening of the goldfield. In 1869 he was appointed a licensed interpreter, in which role he assisted both the Crown and private individuals to acquire Maori land. Some of these transactions created controversy, and he was accused of tricking Maori. In 1875 his attempt to use his position as James Mackay’s interpreter to acquire a lease of land at Tairua for his own financial gain provoked much criticism, and his ‘irregular practices’ led to his dismissal as a licensed interpreter in 1883. He would continue to act for individuals as both an interpreter and a land agent in Ohinemuri and Te Aroha in subsequent years.
Guilding’s close links with Maori were in part explained by his private life. Having married a ‘half-caste’ who later left him for another man, he had three more ‘marriages’ and several more children, who were brought up in Pakeha ways. Financially, he always struggled, filing as bankrupt twice and dying in straightened circumstances. At Te Aroha he held several minor official positions, sometimes being criticized for his performance. Active in local politics, he was generally unpopular and was never elected to the positions he sought. Throughout his life his reputation amongst a sizeable number of his contemporaries was poor.

year: 2016