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Steel Construction Published the List of Highly Influential Articles of 2020
2020 Vol. 35, No. 6
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2020, 35(6): 1-40.
doi: 10.13206/j.gjgS20052505
Abstract
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Abstract:
The application of high-strength steel in steel structures can reduce steel consumption and increase the cost efficiency of steel structures in terms of welding work, transportation and installation. Due to the different mechanical properties between high-strength steel and normal-strength steel, domestic and foreign researchers have carried out a number of studies to support the application of high-strength steel in structures. In addition to the design of high-strength steel members, the efficient design of connections between high-strength steel members are also necessary for the successful application of the high-strength steel structure in engineering practice. This paper introduces the research progress of the two important connection methods, welded and bolted connections, of high-strength steel structures, including the research progress on load-bearing performance of high-strength steel butt welded joints and fillet welded joints, the bearing performance of slip-critical bolted connections and bearing-type bolted connections, as well as the resistance of Grade 12.9 high-strength bolts to hydrogen-induced delayed fracture (HIDF). The existing research conclusions and recent research progress in Tongji University are summarized and highlighted, and the prospection of future research work is presented.
The application of high-strength steel in steel structures can reduce steel consumption and increase the cost efficiency of steel structures in terms of welding work, transportation and installation. Due to the different mechanical properties between high-strength steel and normal-strength steel, domestic and foreign researchers have carried out a number of studies to support the application of high-strength steel in structures. In addition to the design of high-strength steel members, the efficient design of connections between high-strength steel members are also necessary for the successful application of the high-strength steel structure in engineering practice. This paper introduces the research progress of the two important connection methods, welded and bolted connections, of high-strength steel structures, including the research progress on load-bearing performance of high-strength steel butt welded joints and fillet welded joints, the bearing performance of slip-critical bolted connections and bearing-type bolted connections, as well as the resistance of Grade 12.9 high-strength bolts to hydrogen-induced delayed fracture (HIDF). The existing research conclusions and recent research progress in Tongji University are summarized and highlighted, and the prospection of future research work is presented.
2020, 35(6): 41-49.
doi: 10.13206/j.gjgS20051201
Abstract:
The steel-concrete composite slim floor has the advantages of small height of the floor structure, good fire resistance, good appearance of the lower surface, easy pipeline laying, and smaller beam height in the economic span, and has been widely used in foreign countries (especially the United Kingdom and Northern Europe). The steel-concrete composite slim floor commonly used in the actual project is SP prestressed hollow slab and deep deck steel plate composite floor. When used in residential buildings, there are the following deficiencies:1) The lower flange of the steel beam is exposed, requiring anti-corrosion and fire protection. 2) The uneven bottom flange of composite slim beam with deep deck needs to be suspended, which increases cost and structural height. 3) SP prestressed hollow slab and deep rib profiled steel plate both are one-way slabs, which results in a large floor thickness, and it is difficult to further reduce the height of the floor, which restricts the application of the steel-concrete composite slim floor in practical projects. To this end, this paper presents the concept of prefabricated concrete hollow slab and composite slim beam with concrete hollow slab. The prefabricated concrete hollow floor is composed of prefabricated concrete hollow slab and cast-in-place concrete, which can achieve two-way force transmission. Because this new type of composite slim beam with concrete hollow slab is different from the traditional SP prestressed hollow slab and deep rib profiled steel plate. In order to study the cooperative working performance and design method of the new composite slim beam with concrete hollow slab, theoretical analysis and experimental study of the bending performance of the new steel-concrete composite slim beam with concrete hollow slab were carried out.
In this paper, two specimens of composite slim beam with concrete hollow slabs were designed and manufactured. The main changing parameters were the opening pattern of steel beam webs and the settings of shear keys. The steel beams are welded unequal flange steel beams, and the floor slabs are prefabricated concrete hollow slab. The steel grade is Q345B, the floor concrete is C35, and the steel bar is HRB400. The calculated length of the test piece is 3 800 mm, and the geometric length is 4 000 mm. Through experiments, the bearing capacity, ductility, deformation performance, crack development, stress and strain development of the new steel-concrete composite flat beam were studied. On the basis of experimental research, a simplified assumption for the calculation of the ultimate bending capacity of prefabricated concrete hollow slab is proposed, and the calculation formula of the ultimate bending capacity of the prefabricated concrete hollow slab is derived based on the failure strength theory.
The following conclusions were obtained through theoretical analysis and experimental research:1) The composite slim beam with concrete hollow slab has excellent bearing capacity and ductility. When the deflection span ratio of the specimen reaches 1/32, the bearing capacity of the specimen has not decreased significantly, and the specimen exhibits the characteristics of ductile failure. 2) When the bottom flange of the steel beam and the tensile steel bar yield, the test piece reaches the yield bearing capacity; when the steel beam full-section yields, the tensile and compression steel bar yields, and the concrete in the compression zone collapses, the test piece reaches the ultimate bearing capacity. Before the peak load, the strain distribution of the concrete and steel beam sections is approximately linear, and the flat section assumption can be used. 3) The calculation formula of the bending capacity of the composite slim beam with concrete hollow slab based on the failure strength theory is in good agreement with the test results and is safe.
The steel-concrete composite slim floor has the advantages of small height of the floor structure, good fire resistance, good appearance of the lower surface, easy pipeline laying, and smaller beam height in the economic span, and has been widely used in foreign countries (especially the United Kingdom and Northern Europe). The steel-concrete composite slim floor commonly used in the actual project is SP prestressed hollow slab and deep deck steel plate composite floor. When used in residential buildings, there are the following deficiencies:1) The lower flange of the steel beam is exposed, requiring anti-corrosion and fire protection. 2) The uneven bottom flange of composite slim beam with deep deck needs to be suspended, which increases cost and structural height. 3) SP prestressed hollow slab and deep rib profiled steel plate both are one-way slabs, which results in a large floor thickness, and it is difficult to further reduce the height of the floor, which restricts the application of the steel-concrete composite slim floor in practical projects. To this end, this paper presents the concept of prefabricated concrete hollow slab and composite slim beam with concrete hollow slab. The prefabricated concrete hollow floor is composed of prefabricated concrete hollow slab and cast-in-place concrete, which can achieve two-way force transmission. Because this new type of composite slim beam with concrete hollow slab is different from the traditional SP prestressed hollow slab and deep rib profiled steel plate. In order to study the cooperative working performance and design method of the new composite slim beam with concrete hollow slab, theoretical analysis and experimental study of the bending performance of the new steel-concrete composite slim beam with concrete hollow slab were carried out.
In this paper, two specimens of composite slim beam with concrete hollow slabs were designed and manufactured. The main changing parameters were the opening pattern of steel beam webs and the settings of shear keys. The steel beams are welded unequal flange steel beams, and the floor slabs are prefabricated concrete hollow slab. The steel grade is Q345B, the floor concrete is C35, and the steel bar is HRB400. The calculated length of the test piece is 3 800 mm, and the geometric length is 4 000 mm. Through experiments, the bearing capacity, ductility, deformation performance, crack development, stress and strain development of the new steel-concrete composite flat beam were studied. On the basis of experimental research, a simplified assumption for the calculation of the ultimate bending capacity of prefabricated concrete hollow slab is proposed, and the calculation formula of the ultimate bending capacity of the prefabricated concrete hollow slab is derived based on the failure strength theory.
The following conclusions were obtained through theoretical analysis and experimental research:1) The composite slim beam with concrete hollow slab has excellent bearing capacity and ductility. When the deflection span ratio of the specimen reaches 1/32, the bearing capacity of the specimen has not decreased significantly, and the specimen exhibits the characteristics of ductile failure. 2) When the bottom flange of the steel beam and the tensile steel bar yield, the test piece reaches the yield bearing capacity; when the steel beam full-section yields, the tensile and compression steel bar yields, and the concrete in the compression zone collapses, the test piece reaches the ultimate bearing capacity. Before the peak load, the strain distribution of the concrete and steel beam sections is approximately linear, and the flat section assumption can be used. 3) The calculation formula of the bending capacity of the composite slim beam with concrete hollow slab based on the failure strength theory is in good agreement with the test results and is safe.
2020, 35(6): 50-54.
doi: 10.13206/j.gjgSE20051201
Abstract:
The new revised national standard GB/T 1591-2018 High Strength Low Alloy Structural Steel was implemented in February, 2019. This revision made many important changes and additiongs, optimized the performamce of steel.
Such changes include steel lower yield change to upper yield strength,strengthenes alloy composition,adds products classification by different rolling processes, such as hot rolling, normalizing and thermomechanical rolling. According to different rolling process, optimized the steel strength index and quality grades, the A grade steel was cancelled. According to different grades and thickness, the quaranteed limits for longitudinal and transverse elongation, impact energy and Carbon equivalent (CEV) index are also specified respectively. Meanwhile, the product thickness are expanded in a large range, the maximum thickness can be 250 mm(for hot rolled and normalized steel) or 120 mm(for thermomechanically rolled steel). Over and above, steel grades and thickness classification are consisted with Europran standards, adapt the needs of overseas projects.
This paper compares and explains the above changs in detail, and gives some suggestions for reasonable selection of steel signal, rolling process categories, quality grades, performance index, etc. Finally, suggests the revised steel strength design values for structural design.
The new revised national standard GB/T 1591-2018 High Strength Low Alloy Structural Steel was implemented in February, 2019. This revision made many important changes and additiongs, optimized the performamce of steel.
Such changes include steel lower yield change to upper yield strength,strengthenes alloy composition,adds products classification by different rolling processes, such as hot rolling, normalizing and thermomechanical rolling. According to different rolling process, optimized the steel strength index and quality grades, the A grade steel was cancelled. According to different grades and thickness, the quaranteed limits for longitudinal and transverse elongation, impact energy and Carbon equivalent (CEV) index are also specified respectively. Meanwhile, the product thickness are expanded in a large range, the maximum thickness can be 250 mm(for hot rolled and normalized steel) or 120 mm(for thermomechanically rolled steel). Over and above, steel grades and thickness classification are consisted with Europran standards, adapt the needs of overseas projects.
This paper compares and explains the above changs in detail, and gives some suggestions for reasonable selection of steel signal, rolling process categories, quality grades, performance index, etc. Finally, suggests the revised steel strength design values for structural design.
2020, 35(6): 55-64.
doi: 10.13206/j.gjgS20052507
Abstract:
Design methods of bending member for AISC 360-16 Specification for Structural Steel Buildings are explained and comparison is made between AISC 360-16 and GB 50017-2017. Design considerations and differences of bending member for two countrys codes are introduced. Three periods of calculation for the beam buckling are used and the calculating formula for elastic period are from formula of the critical force for beams flexure-torsion buckling, which are same as GB 50017-2017. The strength calculation of flexural member is listed in Chapter F of AISC 360-16, in which the flexural strength is Mn; the design flexural strength takes ϕbMn; the flexural resistance coefficient ϕb=0. 9.
Design methods of bending member for AISC 360-16 Specification for Structural Steel Buildings are explained and comparison is made between AISC 360-16 and GB 50017-2017. Design considerations and differences of bending member for two countrys codes are introduced. Three periods of calculation for the beam buckling are used and the calculating formula for elastic period are from formula of the critical force for beams flexure-torsion buckling, which are same as GB 50017-2017. The strength calculation of flexural member is listed in Chapter F of AISC 360-16, in which the flexural strength is Mn; the design flexural strength takes ϕbMn; the flexural resistance coefficient ϕb=0. 9.
