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1Photography｜1：和航／Wako｜2：日建設計／Nikken SekkeiReducing Construction Time and Cost While Assuring Construction Safety and Minimizing Opportunity Loss The new concept in retrofit bracing installed above the roof drastically reduced the cumbersome work of relocating existing production equipment and plumbing as well as con-struction time and cost. As interruptions to production due to construction were minimized, the client’s business also greatly benefited from the new concept. In order to install on-roof seismic reinforcement, tem-porary holes were made on the roof surface and posts installed directly above the existing columns. The two-part construction method used to install the posts proved high-ly effective in preventing rainwater from entering and dust from spreading inside the building. The new technique kept the opening of the roof slab to a minimum. Adequate water-proofing measures were provided during construction, and the seismic retrofit work above the roof was completed with-out incident. Good client, construction-manager, and design-builder partnership brought this innovative idea into being and made possible its implementation.1 :耐震補強後の屋根面全景。網目状に見えるのが屋根上耐震ブレース。2 : 既存の柱の直上に新設した束材と耐震ブレース。赤いラインは大梁を示している。1 : Photo showing the overall roof aer the installation of the seismic reinforcements. e diagonal net-like structure is the above-the-roof seismic bracing.2 : New post members installed directly onto the existing columns and seismic bracing. e red lines indicate girder locations..耐震ブレースを屋根上に設置することで工期を半減Braces installed above the roof enabled the construction period to be halved既存の柱｜Existing steel column既存の配管｜Existing pipes既存のダクト｜Existing ducts屋根Roof既存の梁｜Existing steel beams一般的な水平ブレースの位置Common location of horizontal braces既存柱の直上に追加した束材Brace connection member added directly onto existing columns水平ブレースHorizontal brace発想の転換による屋内工事の最小化｜Minimizing the Interior Construction by inking Outside the Box耐震補強部廻り断面図｜Section through the seismically reinforced area耐震補強部材設置のステップ｜Steps for installing seismic reinforcement membersStep 32段目の束材は外側から溶接Welding the second part of the post from the outsideStep 21段目の束材を内側から溶接Welding the first part of the post from the insideStep 1屋根スラブを開口（最小限）Make openings in the roof slab (keep to minimum)屋根Roof下部部材Bottommember溶接Weld上部部材Top memberブレースBrace溶接Weld212019 AUTUMN40Feature | WORKS