JPS6156362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an effective means for promoting melting of snow and ice on a bridge surface during snowfall in winter or in cold regions, preventing freezing of the bridge surface, and also preventing freezing of the deck itself. The purpose is to

In snowy or cold regions, the paved surfaces of bridges are at risk of causing traffic accidents due to slips during the winter due to snowfall or ice, impeding vehicular traffic and impairing logistics. Furthermore, the floor slab itself is constantly subject to deterioration due to repeated freezing and thawing processes, resulting in severe damage and the current situation is that it costs a lot of money to maintain and manage.

The present invention promotes melting of snow and ice on the bridge surface and prevents freezing of the bridge surface and the deck itself by heating the deck from below by installing electric heaters on the underside of the bridge and forming a heat insulating layer using heat insulating material. This is done by blocking the cold air and keeping the floorboards warm.

Generally, the internal temperature of a floor slab is different during the day and at night, and decreases as the outside temperature decreases at night. In snowy or cold regions, the outside temperature is almost below freezing, so the internal temperature of the deck slab is also below freezing, so the moisture inside the deck freezes, and along with the freezing, snowfall and melted water on the bridge surface also freezes.

Therefore, it prevents the temperature inside the floor slab from decreasing, and
Preventing the bridge surface from falling below freezing will help prevent snowfall and moisture from freezing on the deck itself and the bridge surface.

In addition, it is known that in bridges over rivers, etc., the wind blowing below the deck removes a considerable amount of heat from the lower surface of the deck, causing a drop in the temperature of the deck, even at night. From this point of view, using an electric heater to heat the underside of the floor slab and forming a heat insulating layer has the effect of preventing a drop in the temperature inside the floor slab.

Next, embodiments of the present invention will be described based on the drawings.

Figure 1 is a cross-sectional view of the bridge in the width direction, where 1 is the pavement surface made of asphalt layer, 2 is the deck slab made of concrete layer, 3 is the girder, and 4 is the railing.

Reference numeral 5 denotes electric heaters, which are installed as a set on the lower surface of the floor slab 2 for each span a, b, and c partitioned by girders 3.

6 is a sub-temperature sensor with each span a,
The temperature of the floor slab 2 is sensed for each span a, b, and c, and the electricity is turned on and off to the electric heaters 5 installed in each span a, b, and c when a main temperature sensor 7, which will be described later, is enabled. It is arranged on the floor slab 2 so that it works.

7 is the main temperature sensor, which is installed on the railing 4 together with the main power terminal board.

A heat insulating material 8 is attached to the lower surface of the floor slab 2 so as to cover the electric heater 5. This insulation material has low thermal conductivity, including inorganic and organic fibrous materials (rock wool, glass fiber, etc.), foam materials (styrofoam, urethane foam, etc.), and powder materials (diatomaceous earth, calcium silicate, etc.). . This heat insulating material 8 is formed as a heat insulating layer or a heat retaining layer.

The electric heater 5, sub-temperature sensor 6, and main temperature sensor 7 are connected by electrical wiring.

A specific example of electrical wiring and control is as shown in Fig. 2. Electrical wiring is applied to the railings, abutments, the lower surface of the floor slab, etc., a waterproof terminal board 9 is attached to the lower surface of the floor slab, and the electric heater 5 is connected to each terminal. Taken from board 9.

The control is such that when the main temperature sensor 7 detects the outside temperature on the main power terminal board 10 senses the outside temperature or the temperature of the bridge structure and the temperature falls below a certain level, for example 0°C or below, the main switch is automatically turned on. Electricity is supplied to the electric heater 5 through the terminal board 9. Furthermore, when the floor slab reaches a certain temperature, for example, 5°C or higher due to the heat generated by the electric heater 5, the sub-temperature sensor 6 of each span detects the temperature and the terminal board 9 is switched off, and the electric heater 5 of that span is no longer energized. When the temperature is stopped and the temperature drops below 5°C, the switch is turned on to supply electricity to the electric heater 5.

Note that the heater wire used in the electric heater is made of an electric resistor such as nichrome or carbon fiber. Further, as the temperature sensor, a known one such as a copper constantan thermoelectric body may be used.

Since the present invention is configured in this way,
That is, the electric heater can warm the bridge from the lower surface of the deck, and heat radiation from the lower surface of the deck can be prevented by the heat insulating layer made of the heat insulating material.

In addition, due to the behavior of the slabs such as deflection and expansion/contraction, the service life of the pavement material is short, so the conventional road heating device installed within the pavement layer is uneconomical as it requires replacing the heating device every time the pavement is reworked. Compared to conventional heating devices, this has the advantage of avoiding the uneconomical cost of replacing the heating device because it is installed under the floor slab.

Furthermore, since this method requires only low power to be applied, that is, it is only necessary to raise the heater temperature to about +20° C., there are few adverse effects caused by temperature gradients in the structure.

Another advantage is that a heating device can be installed at the same time as bridge repairs such as deck slab reinforcement.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an explanatory cross-sectional view in the width direction of a bridge in which the present invention is implemented, and FIG. 2 is an explanatory diagram showing wiring and control. In the drawing, 1 is the pavement surface, 2 is the floor slab, 3 is the girder, 4 is the railing, 5 is the electric heater, 6 is the sub temperature sensor, 7 is the main temperature sensor, 8 is the insulation material, 9 is the terminal board, 10 is the This is the main power terminal board.

Claims (1)

[Claims] 1. An electric heater is installed on the underside of the floor slab, the underside of the floor slab is covered with a heat insulating material, and the electric heater is turned on and off by sensing a certain temperature in a certain range where the electric heater is installed. It consists of a working sub-temperature sensor and a main temperature sensor that is installed at any location and works to detect the outside temperature or the temperature of a part of the bridge structure and turn on and off the main power supply. When the outside air temperature or the temperature of a part of the bridge structure is sensed, electricity starts flowing, and the electric heater generates heat.In order to control the heat generation, the sub-temperature sensor senses the deck temperature and turns on the electric heater in a certain range. A bridge freezing prevention method characterized by turning on and off.