LUD-seismic reinforcement-I-Con. Co.,Ltd.

outline

Shock transmission devices, called LUD (Lock Up Device) or STU (Shock Transmission Units), are used when structures (bridges, buildings, etc.) are subjected to high-speed loading of external shocks and vibrations such as wind and earthquakes, reloading, and pistons being locked. A device that transmits a load. Im. For slow, constant behavior of structures due to creep, shrinkage, and temperature changes, moving slowly through an orifice that is very narrow compared to the cylinder cross-section produces very small response loads that have no effect on the structure. However, high-velocity loads such as seismic loads and vehicle braking loads cannot be moved at high speeds through very narrow orifices and are resisted. shown and the impact load is distributed. The reason why the STU/LUD, which is an impact transmission or dispersion device, exhibits differentiated behavior characteristics for slow and fast movement is due to the internal viscous fluid exhibiting the characteristics and viscosity of the mechanical device consisting of the cylinder, piston and orifice. It can be said that it is caused by .

behavior curve

constant behavior

Behavior during an earthquake

One-point fixed continuous bridge

Excessive seismic force acts on the fixed end piers of the existing single-point fixed continuous bridges. constrained to By doing so, the seismic force will be properly shared and resisted not only on the fixed end piers but also on the piers where LUDs or STUs are installed.
However, due to the increase in the horizontal stiffness of the entire bridge due to multi-point fixing, the effect of lowering the natural period occurs, and the seismic force increases as the period of the bridge decreases. In addition, if the heights of the fixed end piers and the piers that will be at multiple points during an earthquake are not the same, the seismic force will be distributed evenly. As a result, a phenomenon occurred in which the seismic force was concentrated on one pier.

Railway Bridge

Railroad bridges are mainly composed of short diameters, and are often in the form of repeated extensions of simple support structures with fixed bases and movable bases installed on each span. A bridge with this structure transmits all the braking load of railway vehicles to the fixed stage piers. Therefore, if the LUD and STU are installed on the movable end piers, the braking load of the rolling stock will be appropriately distributed and transmitted to the movable end piers. The most economical way to increase Im.

pros and cons

Load reduction and displacement restraint

Since the member force applied only to the fixed end piers in the LUD or STU installation is also shared by the movable end piers, the concentrated load is reduced and the displacement response generated in the structure is reduced by increasing the lateral rigidity of the bridge. prevent earthquake damage.

Optimization design applying commercial structural analysis program

Easily analyzed with common commercial structural analysis programs, economically reducing the cost of constructing structures

Reduction of construction costs and shortening of construction period

Since LUD and STU are small and easy to install, performance improvement costs are lower than the back-front replacement method. In addition, traffic control is unnecessary when improving the performance of existing bridges, and performance can be improved while using the existing bridge abutments as they are.

Maintenance free

LUDs and STUs have almost no temperature dependence, do not transmit thermal stresses for long-term loads (temperature loads) to the lower piers, do not require separate auxiliary equipment or external power, and do not change in performance after large earthquakes. , can be used continuously.

품질시험(Quality Control Test)

종류	구분	설계치 (기준치)	관련기준
고속시험 Fast Movement Test	시험속도	25mm/sec 이상	AASHTO Section 32
	시험하중	설계값
	회전수	25회
	기준치 만족	밀림량 ±12mm 이내 또는 설계자 요구값
저속시험 Slow Movement Test	왕복 횟수	3회	AASHTO Section 32
	시험속도	0.01mm/sec 이상
	시험변위	설계스트로크
	기준치 만족	공칭축력의 10% 이내
시 편 수		규격별 시편 1EA

선정시험(Prototype Test)

종류	구분	설계치 (기준치)	관련기준
내구성시험 Fatigue Load Test	시험속도	1Hz 이상	AASHTO Section 32
	회전수	100,000회
	시험 스트로크	±2mm이상
	기준치 만족	외관 이상 유무
고압시험 Hydrostatic Pressure Test	횟수	1회	AASHTO Section 32
	시험 지속시간	최소 3분
	시험하중	설계값의 150% 이상
	기준치 만족	떨어진 압력이 5% 이내, 외관 이상 유무

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