122 



THE INDIA RUBBER WORLD 



[January i, 1910. 



sheets or specially designed sections Some systems employ 

 regular commercial iron or steel, some use sections specially 

 made for the purpose, and others have special sections and special 

 methods of placing and using them. '1 he object of all systems 

 of reinforcement is to assist the concrete to resist those stresses 

 that it cannot itself carry. In designing reinforcement the con 

 Crete is generally allowed to carry none but compressive stress 

 and the metal is si' placed as to resist practically all other.-,. 



It is generally understood that a load on a horizontal beam 

 causes a tendency to deflect and that this produces a tension in 

 the lower part of it and compression in the upper portions. The 

 tensile stresses are resisted lie metal placed near the bottom sur- 

 face. If the beam is continuous over a support instead of simply 

 resting upon it there is also tension along the upper part at the 

 support. This necessitates metal to resist it. In addition there 

 is the tendency for the upper and lower parts to slide horizontally 

 on one another as sheets slide when a book or pile of paper is 

 bent. When this sliding, of sheering, tendency exceeds the 

 strength of the concrete to withstand such action it is necessary 

 to provide reinforcement to hold it. For this purpose metal is 

 placed vertically or diagonally in the beam. It may be done by 

 stirrups separate from the main reinforcing bars, by bending up 

 some of the bars near the supports, or by reinforcement made of 

 specially designed section-, of metal for this purpose. It will 

 thus be seen that the design of a beam involves not only provision 

 for taking care of the tension in its lower portions, but also the 

 tension and sheering stresses in other parts. In most concrete 

 buildings the beams are an integral part of the whole structure 

 instead of simply resting on supports, and the stresses are more 

 complicated than in ordinary timber construction. 



An important feature in a reinforced concrete building is its 

 monolithic character. Instead of a collection of parts with 

 or Irs- fastening together it has its walls, columns, beams. 

 floors, and roof formed into 1 ne m;i- and so tied together by 

 metal reinforcement that the concrete has little to do except 

 resist compressive stresses. The floor reinforcement is carried 

 over the beams and the beams and floor become one mass ; there 

 is thus none of the weakening or lack of continuity that occurs 

 in a wooden building where one floor plank ends and the next 

 begins. In the same manner the reinforcement is so designed 

 and placed as to tie the end- of the beams into the columns and 

 outside walls or pilasters. The column reinforcement extends 

 continuously from the column of one story into that of the story 

 above. This monolithic construction gives the greatest possible 

 rigidity and forms a structure that is free from vibration, no 

 matter what kind of machinery is operated in it. A conclusive 

 proof of rigidity has been furnished by the behavior of rein- 

 forced concrete buildings during some of the earthquakes of 

 recent years. Such rigidity and freedom from vibration must 

 of necessity decrease the wear of the machinery, thus adding 

 to its life and reducing the cost of repairs. 



It is quite evident that a building of reinforced concrete must 

 be fireproof. It commonly has no woodwork in its construction 

 except the window frames and sashes, and these can be of metal 

 if desired. Sprinkler systems are generally installed to protect 

 the contents, though the building itself does not need them. 



The question of the installation of piping, shafting, electric 

 wiring, and so on, is one that arises and is frequently considered 

 as a great objection to a concrete building. For sprinkler piping 

 supports it is common to provide cast iron sockets set in the 

 concrete and threaded to receive the pipe hangers. It is easy 

 to mark their location on the wooden forms before the concrete 

 floor slabs are poured. The cost of these sockets and setting 

 them in place is a small item. In the same way sockets can be 

 set for hanger bolts to support shafting, motors, and the like, 

 providing their location is determined before the building is 

 erected. For holding down machinery and for electric wiring 

 it is a simple matter to drill the necessary holes and use expan- 



sion bolts, or for small work wooden plugs can be driven into 

 the holes and screws used in them. A pneumatic drill is a rapid 

 and economical means lor such drilling. 



Larger window area can lie obtained in a concrete building 

 than with brick and timber construction and the lightness of 

 the interior much increased on this account. In the case of a 

 concrete rubber factory building designed by the writer the win- 

 dow area is about 65 per cent, of the wall space of each story, 

 while a similar building of brick and timber construction has a 

 window area about 25 per cent. less. 



Rapidity of construction is frequently a point of advantage in 

 favor of concrete. There is generally little or no delay in getting 

 cement and steel reinforcement, while a building using heavy 

 timbers or steel beams is liable to have a long wait for material 

 unless ordered a long time before required. Such lumber as is 

 required for centering is readily obtainable and work on it can 

 be started without delay. 



Instead of making the outside walls entirely of concrete it is 

 quite common to use brick or tile for the curtain walls between 

 the pilasters. In some cases this reduces the cost and to some 

 the architectural effect is pleasing. If ornamentation or archi- 

 tectural embellishment is desired on a concrete building it can 

 be obtained to any desired extent. The surface of the concrete 

 can be hammered to resemble cut stone, or various surface 

 finishes can be given by acid treatment or washing the surface 

 after removing the forms before the concrete has hardened. 



The question of cost is an important one to owners and we 

 are constantly asked how reinforced concrete compares with brick 

 and timber in this respect. No general reply can properly be 

 made, as so much depends upon the conditions pertaining to each 

 case. Generally speaking, the cost of concrete buildings for light 

 floor loads is more than the common mill construction. As the 

 door loads increase, or if long spans and few posts are desired, 

 tie cost is more favorable to concrete, and for warehouses and 

 heavily loaded structures concrete is usually cheaper. But in 

 addition to the question of cost there are many reasons why this 

 comparatively new system of construction merits careful atten- 

 tion from the manufacturer wdien he is considering the question 

 of new buildings. 



BLOODSHED OVER RUBBER. 



THE article headed " 'Red Rubber' in Eastern Peru," in The 

 India Rubber World, November 1, 1009 (page 44"), is re- 

 called by reports of subsequent proceedings in the British parlia- 

 ment. Upon inquiry being made as to whether further reports 

 as to the Peruvian Amazon Co. had been received, Mr. McKinnon 

 Wood, replying for the government, said that only unofficial 

 reports had come to hand. But he was in communication with 

 the Peruvian company on the subject of the alleged cruelties. 

 The British ambassador at Washington had verified the reports 

 of injuries inflicted upon two American citizens in the rubber 

 region, and the payment of compensation on the part of Peru. 



INDIANS KILL A "CAUCHERO." 



At the beginning of September was assassinated in Rio das 

 Pedras, a tributary of the Madre de Dios, in southern Peru, a 

 well known cauchero, Carlos Scharff. The act was that of some 

 of his workmen, who charged him with barbarous treatment. 

 The Indians of that region, which is hundreds of miles south 

 of the Putumayo, the scene of the outrages described by the 

 British press, are of the less tractable tribes Piros and Anahuacas. 



According to the Manaos newspaper Amazonas, Scharff had 

 lately collected about 500 tons of caucho. A Spaniard named 

 Rodrigues, resident in Ucayali and an aviador of Scharff, had 

 organized an expedition to Rio Tacauahamano to try and save 

 this rubber. Creditors of Scharff down the Amazon were also 

 sending representatives to Peru to protect their interests. He is 

 reported to have owed in Para. Manaos and Iquitos $3,000,000. 



